0216tool_xiaoye
Version:
叶永洁自定义工具函数库
74 lines (63 loc) • 1.49 kB
HTML
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>测试各种遍历数组的效率</title>
</head>
<body>
<script>
/*
测试: for...in / for / forEach / keys&forEach / while / for...of
耗时: keys&forEach | for...in | for..of >>> for | forEach | while
*/
const arr = new Array();
for (let i = 0; i < 100000; i++) {
arr.push(1)
}
//for..of
console.time()
for (const key of arr) {
let element = arr[key];
}
console.timeEnd()
// for..in // 会查找原型链
console.time()
for (const key in arr) {
let element = arr[key];
}
console.timeEnd()
//for
console.time()
for (let index = 0; index < arr.length; index++) {
let element2 = arr[index];
}
console.timeEnd()
// forEach
console.time()
arr.forEach(item => {
let element3 = item;
})
console.timeEnd()
// keys() + forEach 多产生了一个数组
console.time()
Object.keys(arr).forEach(index => {
let element32 = arr[index]
})
console.timeEnd()
// while
console.time()
const length = arr.length
let index = 0
while(index++ < length) {
let element4 = arr[index]
}
console.timeEnd()
// for..of // 会查找原型链
console.time()
for (const value of arr) {
}
console.timeEnd()
</script>
</body>
</html>