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关于js中几种遍历方法性能的测试

2017-07-21 16:38 471 查看
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<script type="text/javascript">
var arr = new Array(10000000);
var arr1 = [];
var arr2 = [];
var arr3 = [];
var arr4 = [];
var arr5 = [];
var arr6 = [];

arr.fill(1);

console.time('for优化版');
for(var i = 0,len = arr.length;i < len;i ++){
arr1.push(arr[i]);
}
console.timeEnd('for优化版');

//for
console.time('for');
for(var i = 0;i < arr.length;i ++){
arr2.push(arr[i]);
}
console.timeEnd('for');

//forEach
console.time('forEach');
arr.forEach(function(val){
arr3.push(val);
});
console.timeEnd('forEach');

//for in
console.time('for in');
for(var b in arr){
arr4.push(arr[b]);
}
console.timeEnd('for in');

//map
console.time('map');
arr.map(function(val){
arr5.push(val);
});
console.timeEnd('map');

//for of
console.time('for of');
for(var d of arr){
arr6.push(arr[d]);
}
console.timeEnd('for of');
</script>
</body>
</html>

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