TypeScript vs. C#: LINQ

一世安逸 發表於 2019-11-10 22:40:00

<h2>TypeScript vs. C#: LINQ</h2>
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<p>TypeScript 没有等效于 LINQ 的语言集成自然查询方面?不能在 TypeScript 中写入以下 LINQ 语句</p>
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<div class="line number1 index0 alt2"><code class="csharp keyword">var</code> <code class="csharp plain">adultUserNames =  </code><code class="csharp keyword">from</code> <code class="csharp plain">u </code><code class="csharp keyword">in</code> <code class="csharp plain">users  </code><code class="csharp keyword">where</code> <code class="csharp plain">u.Age >= 18  </code><code class="csharp keyword">select</code> <code class="csharp plain">u.Name;</code></div>
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<p>但是，位于 LINQ 核心的 iE6<T>扩展方法在 TypeScript 中具有等效项（或可以模拟）。</p>
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<div class="line number1 index0 alt2"><code class="csharp plain">Aggregate</code></div>
<div class="line number2 index1 alt1"><code class="csharp plain">All</code></div>
<div class="line number3 index2 alt2"><code class="csharp plain">Any</code></div>
<div class="line number4 index3 alt1"><code class="csharp plain">Append</code></div>
<div class="line number5 index4 alt2"><code class="csharp plain">Average</code></div>
<div class="line number6 index5 alt1"><code class="csharp plain">Cast</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">Concat</code></div>
<div class="line number8 index7 alt1"><code class="csharp plain">Contains</code></div>
<div class="line number9 index8 alt2"><code class="csharp plain">Count</code></div>
<div class="line number10 index9 alt1"><code class="csharp plain">DefaultIfEmpty</code></div>
<div class="line number11 index10 alt2"><code class="csharp plain">Distinct</code></div>
<div class="line number12 index11 alt1"><code class="csharp plain">ElementAt</code></div>
<div class="line number13 index12 alt2"><code class="csharp plain">ElementAtOrDefault</code></div>
<div class="line number14 index13 alt1"><code class="csharp plain">Empty</code></div>
<div class="line number15 index14 alt2"><code class="csharp plain">Except</code></div>
<div class="line number16 index15 alt1"><code class="csharp plain">First</code></div>
<div class="line number17 index16 alt2"><code class="csharp plain">FirstOrDefault</code></div>
<div class="line number18 index17 alt1"><code class="csharp plain">List.ForEach</code></div>
<div class="line number19 index18 alt2"><code class="csharp plain">GroupBy</code></div>
<div class="line number20 index19 alt1"><code class="csharp plain">Intersect</code></div>
<div class="line number21 index20 alt2"><code class="csharp plain">Last</code></div>
<div class="line number22 index21 alt1"><code class="csharp plain">LastOrDefault</code></div>
<div class="line number23 index22 alt2"><code class="csharp plain">Max</code></div>
<div class="line number24 index23 alt1"><code class="csharp plain">Min</code></div>
<div class="line number25 index24 alt2"><code class="csharp plain">OfType</code></div>
<div class="line number26 index25 alt1"><code class="csharp plain">OrderBy / ThenBy</code></div>
<div class="line number27 index26 alt2"><code class="csharp plain">Reverse</code></div>
<div class="line number28 index27 alt1"><code class="csharp plain">Select</code></div>
<div class="line number29 index28 alt2"><code class="csharp plain">SelectMany</code></div>
<div class="line number30 index29 alt1"><code class="csharp plain">Single</code></div>
<div class="line number31 index30 alt2"><code class="csharp plain">SingleOrDefault</code></div>
<div class="line number32 index31 alt1"><code class="csharp plain">Skip</code></div>
<div class="line number33 index32 alt2"><code class="csharp plain">SkipWhile</code></div>
<div class="line number34 index33 alt1"><code class="csharp plain">Sum</code></div>
<div class="line number35 index34 alt2"><code class="csharp plain">Take</code></div>
<div class="line number36 index35 alt1"><code class="csharp plain">TakeWhile</code></div>
<div class="line number37 index36 alt2"><code class="csharp plain">Union</code></div>
<div class="line number38 index37 alt1"><code class="csharp plain">Where</code></div>
<div class="line number39 index38 alt2"><code class="csharp plain">Zip</code></div>
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<h3>Aggregate</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">leftToRight = users.Aggregate(initialValue, (a, u) => </code><code class="csharp comments">/* ... */</code><code class="csharp plain">);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">leftToRight = users.reduce((a, u) => </code><code class="csharp comments">/* ... */</code><code class="csharp plain">, initialValue);</code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">rightToLeft = users.reduceRight((a, u) => </code><code class="csharp comments">/* ... */</code><code class="csharp plain">, initialValue);</code></div>
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<h3>All</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">allReady = users.All(u => u.IsReady);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScrip</code></div>
<div class="line number5 index4 alt2"><code class="csharp plain">tconst allReady = users.every(u => u.isReady);</code></div>
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<h3>Any</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">isDirty = users.Any(u => u.IsDirty);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">isDirty = users.some(u => u.isDirty);</code></div>
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<h3>Append</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">allUsers = users.Append(oneMoreUser);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">allUsers = [ ...users, oneMoreUser ];</code></div>
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<h3>Average</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">avgAge = users.Average(u => u.Age);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">if</code> <code class="csharp plain">(users.length < 1) { </code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">throw</code> <code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'source contains no elements'</code><code class="csharp plain">);</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">}</code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">avgAge = users.reduce((a, u) => a + u.age, 0) / users.length;</code></div>
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<h3>Cast</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">people = users.Cast<Person>();</code></div>
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<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">people = users </code><code class="csharp keyword">as</code> <code class="csharp plain">Person[];</code></div>
<div class="line number6 index5 alt1"><code class="csharp comments">// Note: not semantically the same. The C# version throws an exception</code></div>
<div class="line number7 index6 alt2"><code class="csharp comments">// if any of the users can't be cast to type Person.</code></div>
<div class="line number8 index7 alt1"><code class="csharp comments">//注意：在语义上不同。C# 版本引发异常如果无法强制转换为键入 Person 的任何用户。　</code></div>
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<h3>Concat</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">allUsers = users.Concat(moreUsers);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">allUsers = [ ...users, ...moreUsers ];</code></div>
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<h3>Contains</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">hasAdmin = users.Contains(admin);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">hasAdmin = users.includes(admin); </code><code class="csharp comments">// Use a polyfill for IE support</code></div>
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<h3>Count</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">n = users.Count();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">n = users.length;</code></div>
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<h3>DefaultIfEmpty</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">nonEmptyUsers = Enumerable.DefaultIfEmpty(users);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">nonEmptyUsers = users.length ? users : [ </code><code class="csharp keyword">null</code> <code class="csharp plain">];　</code></div>
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<h3>Distinct</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">uniqueNames = users.Select(u => u.Name).Distinct();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">uniqueNames = Object.keys(users.map(u => u.name).reduce((un, u) => ({ ...un, n }),{}));</code></div>
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<h3>ElementAt</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">nth = users.ElementAt(n);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">if</code> <code class="csharp plain">(n < 0 || n > users.length) { </code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">throw</code> <code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'Index was out of range'</code><code class="csharp plain">);</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">}</code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">nth = users;　</code></div>
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</div>
</div>
<h3>ElementAtOrDefault</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">nth = users.ElementAtOrDefault(n);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">nth = users;</code></div>
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<h3>Empty</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">noUsers = IEnumerable.Empty<User>();</code><code class="csharp comments">//?.NET 4.0 没找到找到的是DefaultIfEmpty</code></div>
<div class="line number3 index2 alt2"><code class="csharp comments">//</code></div>
<div class="line number4 index3 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">noUsers = IEnumerable.DefaultIfEmpty<User>();</code></div>
<div class="line number5 index4 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number6 index5 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number7 index6 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">noUsers: User[] = [];</code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">noUsers = [] </code><code class="csharp keyword">as</code> <code class="csharp plain">User[];</code></div>
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</div>
<h3>Except</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">maleUsers = users.Except(femaleUsers);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">maleUsers = users.filter</code></div>
<div class="line number6 index5 alt1"><code class="csharp plain">(</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">u =>  !femaleUsers.includes(u) </code><code class="csharp comments">// Use a polyfill for IE support（Use a polyfill for IE support）</code></div>
<div class="line number8 index7 alt1"><code class="csharp plain">);　</code></div>
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</div>
<h3>First</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">first = users.First();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">if</code> <code class="csharp plain">(users.length < 1) { </code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">throw</code> <code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'Sequence contains no elements'</code><code class="csharp plain">);</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">}</code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">first = users;</code></div>
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</div>
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<h3>FirstOrDefault</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">first = users.FirstOrDefault();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">first = users;</code></div>
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</td>
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</div>
<h3>List.ForEach</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp plain">users.ToList().ForEach(u => </code><code class="csharp comments">/* ... */</code><code class="csharp plain">);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp plain">users.forEach(u => </code><code class="csharp comments">/* ... */</code><code class="csharp plain">);</code></div>
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</div>
</div>
<h3>GroupBy</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">usersByCountry = users.GroupBy(u => u.Country);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">usersByCountry = users.reduce((ubc, u) =></code></div>
<div class="line number6 index5 alt1"><code class="csharp plain">({ </code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">...ubc, </code></div>
<div class="line number8 index7 alt1"><code class="csharp plain">: [ ...(ubc || []), u ],}),</code></div>
<div class="line number9 index8 alt2"><code class="csharp plain">{});</code></div>
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</div>
<h3>Intersect</h3>
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<div class="line number5 index4 alt2">5</div>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">targetUsers = usersWhoClicked.Intersect(usersBetween25And45);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">targetUsers = usersWhoClicked.filter(u =>  usersBetween25And45.includes(u) </code><code class="csharp comments">// Use a polyfill for IE support);</code></div>
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</div>
</div>
<h3>Last</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">last = users.Last();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScrip</code></div>
<div class="line number5 index4 alt2"><code class="csharp plain">tif (users.length < 1) { </code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">throw</code> <code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'Sequence contains no elements'</code><code class="csharp plain">);</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">}</code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">last = users;</code></div>
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</td>
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</tbody>
</table>
</div>
</div>
<h3>LastOrDefault</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">last = users.LastOrDefault();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">last = users;</code></div>
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</table>
</div>
</div>
<h3>Max</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">oldestAge = users.Max(u => u.Age);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScrip</code></div>
<div class="line number5 index4 alt2"><code class="csharp plain">tif (users.length < 1) { </code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">throw</code> <code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'source contains no elements'</code><code class="csharp plain">);</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">}</code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">oldestAge = users.reduce((oa, u) => Math.max(oa, u.age), 0);</code></div>
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</table>
</div>
</div>
<h3>Min</h3>
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<td class="code">
<div class="container">
<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">youngestAge = users.Min(u => u.Age);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">if</code> <code class="csharp plain">(users.length < 1) {  t</code></div>
<div class="line number6 index5 alt1"><code class="csharp plain">hrow </code><code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'source contains no elements'</code><code class="csharp plain">);</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">}</code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">youngestAge = users.reduce((ya, u) => Math.min(ya, u.age), Number.MAX_VALUE);</code></div>
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</tbody>
</table>
</div>
</div>
<h3>OfType</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">bots = users.OfType<Bot>();</code><code class="csharp comments">//根据类型刷新元素</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp comments">// No equivalent   无等效项</code></div>
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</td>
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</tbody>
</table>
</div>
</div>
<h3>OrderBy / ThenBy</h3>
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<div class="line number1 index0 alt2">1</div>
<div class="line number2 index1 alt1">2</div>
<div class="line number3 index2 alt2">3</div>
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<td class="code">
<div class="container">
<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">sorted = users.OrderBy(u => u.Age).ThenBy(u => u.Name);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">sorted = users.sort((a, b) => { </code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">ageDiff = b.age - a.age; </code></div>
<div class="line number7 index6 alt2"><code class="csharp keyword">if</code> <code class="csharp plain">(ageDiff)</code></div>
<div class="line number8 index7 alt1"><code class="csharp spaces">  </code><code class="csharp keyword">return</code> <code class="csharp plain">ageDiff; </code></div>
<div class="line number9 index8 alt2"><code class="csharp keyword">return</code> <code class="csharp plain">a.name.localeCompare(b.name);</code></div>
<div class="line number10 index9 alt1"><code class="csharp comments">// Use a polyfill for IE support</code></div>
<div class="line number11 index10 alt2"><code class="csharp plain">}</code></div>
<div class="line number12 index11 alt1"><code class="csharp plain">);</code></div>
</div>
</td>
</tr>
</tbody>
</table>
</div>
</div>
<h3>Reverse</h3>
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<td class="gutter">
<div class="line number1 index0 alt2">1</div>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">backwards = users.Reverse();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">backwards = users.reverse();</code><code class="csharp comments">// Caution: users is also reversed! 原数组也翻转了</code></div>
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<h3>Select</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">names = users.Select(u => u.Name);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">names = users.map(u => u.name);　　</code></div>
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<h3>SelectMany</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">phoneNumbers = users.SelectMany(u => u.PhoneNumbers);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">phoneNumbers = users.reduce((pn, u) => [ ...pn, ...u.phoneNumbers ], []);　</code></div>
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<h3>Single</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">user = users.Single();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">if</code> <code class="csharp plain">(users.length > 1) { </code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">throw</code> <code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'The input sequence contains more than one element'</code><code class="csharp plain">);</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">}</code><code class="csharp keyword">else</code> <code class="csharp keyword">if</code> <code class="csharp plain">(!users.length) { </code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">throw</code> <code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'The input sequence is empty'</code><code class="csharp plain">);</code></div>
<div class="line number9 index8 alt2"><code class="csharp plain">}</code></div>
<div class="line number10 index9 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">user = users;</code></div>
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<h3>SingleOrDefault</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">user = users.Single();</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">user = users;　</code></div>
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<h3>Skip</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">otherUsers = users.Skip(n);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">otherUsers = users.filter((u, i) => i >= n);　</code></div>
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<h3>SkipWhile</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">otherUsers = users.SkipWhile(predicate);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">let</code> <code class="csharp plain">i = 0;</code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">while</code> <code class="csharp plain">(i < users.length && predicate(users));</code></div>
<div class="line number7 index6 alt2"><code class="csharp spaces">   </code><code class="csharp keyword">const</code> <code class="csharp plain">otherUsers = users.slice(i - 1);　</code></div>
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<h3>Sum</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">totalYears = users.Sum(u => u.Age);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">if</code> <code class="csharp plain">(users.length < 1) { </code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">throw</code> <code class="csharp keyword">new</code> <code class="csharp plain">Error(</code><code class="csharp string">'source contains no elements'</code><code class="csharp plain">);</code></div>
<div class="line number7 index6 alt2"><code class="csharp plain">}</code></div>
<div class="line number8 index7 alt1"><code class="csharp keyword">const</code> <code class="csharp plain">totalYears = users.reduce((ty, u) => ty + u, 0);</code></div>
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</div>
</div>
<h3>Take</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">otherUsers = users.Take(n);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">otherUsers = users.filter((u, i) => i < n);</code></div>
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</table>
</div>
</div>
<h3>TakeWhile</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">otherUsers = users.TakeWhile(predicate);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">let</code> <code class="csharp plain">i = 0;</code></div>
<div class="line number6 index5 alt1"><code class="csharp keyword">while</code> <code class="csharp plain">(i < users.length && predicate(users));</code></div>
<div class="line number7 index6 alt2"><code class="csharp spaces">  </code><code class="csharp keyword">const</code> <code class="csharp plain">otherUsers = users.slice(0, i - 1);　</code></div>
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</div>
<h3>Union</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">allUsers = someUser.Union(otherUsers);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">allUsers = otherUsers.reduce((au, u) => </code></div>
<div class="line number6 index5 alt1"><code class="csharp spaces"> </code><code class="csharp plain">au.includes(u)  ? au    : [ ...au, u ]}), someUsers));</code><code class="csharp comments">// Use a polyfill for IE support</code></div>
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</div>
<h3>Where</h3>
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">adults = users.Where(u => u.Age >= 18);</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">adults = users.filter(u => u.age >= 18);　</code></div>
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</table>
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</div>
<h3>Zip</h3>
<div class="cnblogs_Highlighter sh-gutter">
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<div class="line number1 index0 alt2"><code class="csharp comments">// C#</code></div>
<div class="line number2 index1 alt1"><code class="csharp keyword">var</code> <code class="csharp plain">matches = buyers.Zip(sellers, (b, s) => </code><code class="csharp keyword">new</code> <code class="csharp plain">{ Buyer = b, Seller = s });</code></div>
<div class="line number3 index2 alt2"><code class="csharp spaces"> </code> </div>
<div class="line number4 index3 alt1"><code class="csharp comments">// TypeScript</code></div>
<div class="line number5 index4 alt2"><code class="csharp keyword">const</code> <code class="csharp plain">matches = []</code></div>
<div class="line number6 index5 alt1"><code class="csharp plain">;</code><code class="csharp keyword">for</code> <code class="csharp plain">(</code><code class="csharp keyword">let</code> <code class="csharp plain">i = 0; i < buyers.length && i < sellers.length; i++) { </code></div>
<div class="line number7 index6 alt2"><code class="csharp spaces"> </code><code class="csharp plain">matches.push({    buyer: buyers,    seller: sellers,  });</code></div>
<div class="line number8 index7 alt1"><code class="csharp plain">}</code></div>
</div>
</td>
</tr>
</tbody>
</table>
</div>
</div>
<p>水平有限，请大家见谅，翻译的有误，请指出。谢谢</p>
<p>原文地址 https://decembersoft.com/posts/typescript-vs-csharp-linq/</p>
</div>
</div>

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来源：https://www.cnblogs.com/sexintercourse/p/11832242.html

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TypeScript vs. C#: LINQ