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[转] console.log的高级用法

<pre class=" CodeMirror-line "><strong>//基本用法</strong></pre>
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<pre>console.log('最常见用法\n换行');<br><br>console.<span class="cm-js-property">error(<span class="cm-js-string">'输出错误信息 会以红色显示');<br><br>console.<span class="cm-js-property">warn(<span class="cm-js-string">'打印警告信息 会以黄色显示');<br><br><span class="cm-tab"><span class="cm-js-variable">console.<span class="cm-js-property">info(<span class="cm-js-string">'打印一般信息');<br><br><span class="cm-tab"><span class="cm-js-variable"><span class="cm-js-property"><span class="cm-js-string">console.<span class="cm-js-property">clear();<span class="cm-js-comment">//清空上面的console显示</span></span></span></span></span></span></span></span></span></span></span></span></span></span></pre>
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<p><strong>//进阶用法</strong></p>
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<pre>console.assert(false,'判断为false才显示的信息');//console.assert(bool,”info”) 如果bool为false 打印出info 否则不打印<br><br>console.table([['中国','美国'],['好']]);//传入的对象或数组以表格方式显示<br><br>function fn(){ console.trace();        }//打印 调用链 fn2()调用fn1()，fn1()调用fn()<br><br>function fn1(){ fn(); }<br><br><span class="hljs-function"><span class="hljs-keyword">function <span class="hljs-title">fn2(<span class="hljs-params">){ fn1(); }<br><br>fn2();</span></span></span></span></pre>
<pre>&nbsp;</pre>
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<p>&nbsp;</p>
<p><strong>&nbsp;//格式化输出</strong></p>
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<div class="hljs-ln-line"><span class="hljs-comment">console.log支持的格式标志有:</span></div>
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<div class="hljs-ln-numbers">&nbsp;<span class="hljs-comment">%s 占位符</span></div>
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<div class="hljs-ln-numbers">&nbsp;<span class="hljs-comment">%d 或 %i 整数</span></div>
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<div class="hljs-ln-numbers">&nbsp;<span class="hljs-comment">%f 浮点数</span></div>
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<div class="hljs-ln-numbers">&nbsp;<span class="hljs-comment">%o%O object对象</span></div>
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<div class="hljs-ln-numbers">&nbsp;<em id="__mceDel"><span class="hljs-comment">%c css样式</span></em></div>
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<pre>console.log('%d + %d = %d',1,2,3);<br>
//%o%O打印dom节点时就不一样
console.log('%o',document.body);
console.log('%O',document.body);<br><br><em id="__mceDel">// %c 后面的内容，增加css样式<br></em><em id="__mceDel">//附：console.log输出的超链接会被自动识别并加上灰色字体颜色和下划线的样式，而这个无法用%c覆盖<br></em><em id="__mceDel">console.log('123 %c 456','font-size:36px;color:red;');<br>console.log('123 %c 4 http://www.google.com 56 %c 789','font-size:20px;color:#ff8400;','font-size：12px;color:#000');<br> <br>//利用css样式加载图片 //没法直接设置width和height样式,line-height图片高度,再调padding <br>console.log('%c ','background-image:url("http://iyeslogo.orbrand.com/150902Google/005.gif");background-size:120% 120%;background-repeat:no-repeat;background-position:center center;line-height:60px;padding:30px 120px;');</em></pre>
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<p>&nbsp;</p>
<p><strong>&nbsp;//高级用法</strong></p>
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<pre>//计时，单位毫秒
    console.time();
    for(var i=0;i&lt;100000;i++){
      var j=i*i;
    }
    console.timeEnd();
//统计代码或函数被调用了多少次
    var fn_ = function(){ console.count('hello world'); }
    for(var i=0;i&lt;5;i++){
      fn_();
    }
//查看内存使用情况，是属性，不带括号
//console.memory;
//在浏览器开发者工具中使用
//分组输出，可嵌套
    console.group('分组1');
    console.log('语文');
    console.log('数学');
      console.group('其他科目');
      console.log('化学');
      console.log('地理');
      console.log('历史');
      console.groupEnd('其他科目');
    console.groupEnd('分组1');</pre>
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<p></audio></p><br><br>
来源：https://www.cnblogs.com/chris-oil/p/11988903.html
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