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Node.JS中用concat和push连接两个或多个数组的性能比较

 5 years ago
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JavaScript中连接两个数组成一旧新数组，常用concat方法，比如：

var arr1 = [1,2,3,-1]
var arr2 = [4,5,6,7,8,9,10,12,13,14,15,16,17,18,29,30,31,32,33,34,35,36,37,38,39,40]
var arr  = arr1.concat(arr2)

借用apply方法 ，push、splice也可和来连接数组。因为push没有创建新数组，如果想要保挂原对象的引用，可使用push方法。

那么两者在node.js的性能如何？ 我们做了一组测试数据，两种分别测试100万次。

var testConcat = function(abc) {
  var arr1 = [1,2,3,-1]
  var arr2 = [4,5,6,7,8,9,10,12,13,14,15,16,17,18,29,30,31,32,33,34,35,36,37,38,39,40]
  var arr  = arr1.concat(arr2)
}

var testPush = function(abc) {
  var arr1 = [1,2,3,-1]
  var arr2 = [4,5,6,7,8,9,10,12,13,14,15,16,17,18,29,30,31,32,33,34,35,36,37,38,39,40]
  Array.prototype.push.apply(arr1, arr2)
}

var count = 1000000

var date = Date.now()
for (var i = 0; i < count; i++) {
    testConcat()
}
console.log(Date.now() - date)

var date = Date.now()
for (var i = 0; i < count; i++) {
    testPush()
}

console.log(Date.now() - date)

结果：

$ node array.js
1470
465

由此可见，push比concat方法快3倍左右。因为push只是在原数组的基础上进行修改，所以会快一点。


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