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  • 【遍历】

    1. 数组

    1.1 for i++

    var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
    for (var i = 0, l = arr.length; i < l; i++) {
        console.log(i, arr[i])
    }

     输出:

    1.2 for l-- 

    var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
    for (var l = arr.length; l--;) {
        console.log(l, arr[l])
    }

    输出: 

    应用: 

    var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
    for (var l = arr.length; l--;) {
        arr.splice(l, 1)
    }
    console.log(arr) // []

    1.3 while l--

    var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
    var l = arr.length
    while(l--) {
        console.log(l, arr[l])
    }

    输出: 

    2.对象

    var obj = {one: 1, two: 2, three: 3}
    for (var key in obj) {
        console.log(key, obj[key])
    }

    输出:

    3. ES5

    var arr = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
    arr.forEach(function(value, index, array) {
        console.log(index, value, array)
    })

     输出:

    4. Underscore.js

    <script src="underscore.js"></script>
    <script>
        var list = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
        _.each(list, function(element, index, list) {
            console.log(element, index, list, this)
        }, list)
    
    
        _.each({one: 1, two: 2, three: 3}, function(value, key, list) {
            console.log(value, key, list)
        })
    </script>

    输出:

    5. jQuery

    <script src="jquery-1.10.2.js"></script>
    <script>
        var list = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
        $.each(list, function(index, value) {
            console.log(index, value)
        })
    
    
        $.each({one: 1, two: 2, three: 3}, function(key, value) {
            console.log(key, value)
        })
    </script>

    输出:

    6.Angular

    angular.forEach(['a', 'b'], function(value, index) {
        console.log(value, index)
    })
    
    angular.forEach({a: 1, b: 2}, function(value, key) {
        console.log(value, key)
    })

    7.Python

    python list遍历

    info = ['a','b','c','d','ee','fff']
    for m in info:
        print m

    for in

    for in 循环

    Object.prototype.bar = 1
    var foo = {goo: undefined}
    for (var p in foo) {
        console.log(p) // goo bar
        if (foo.hasOwnProperty(p)) {
            console.log('hasOwnProperty', p) // goo
        }
    }
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  • 原文地址:https://www.cnblogs.com/jzm17173/p/5809580.html
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