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将javascript对象强制转换为数组。如何?

jquery javascript

Jhonny D. Cano -Leftware- · 技术社区 · 15 年前

我做了这个沙盒测试:

<html>
    <head>
        <title>whatever</title>
        <script type="text/javascript">
            function myLittleTest() {
                var obj, arr, armap;

                arr = [1, 2, 3, 5, 7, 11];

                obj = {};
                obj = arr;
                alert (typeof arr);
                alert (typeof obj);

                // doesn't work in IE
                armap = obj.map(function (x) { return x * x; });
                alert (typeof armap);

            }
            myLittleTest();
        </script>
    </head>
    <body>
    </body>
</html>

我意识到我可以使用jquery的函数$.map使代码行正常工作,但是,我在javascript数据类型上缺少什么?

6 回复 | 直到 12 年前

Mike Morearty NiCk Newman 12 年前

Array.map() http://msdn.microsoft.com/en-us/library/k4h76zbx(v=VS.85).aspx http://msdn.microsoft.com/en-us/library/ff679976(v=VS.94).aspx

Marek Sebera 13 年前

arguments Array.prototype.slice.call(o)

var o = {0:"a", 1:'b', length:2};
var a = Array.prototype.slice.call(o);

a ["a", "b"] length

Taryn Frank Pearson 13 年前

var obj = {a: 1, b: 2, c: 3};

var arr = $.map(obj, function (value, key) { return value; });

var arr = $.map(obj, function (value, key) { return key; });

Adaddinsane 13 年前

http://api.jquery.com/jQuery.makeArray/

Peter Ajtai 15 年前

for

this Perfection Kills page

Object.prototype.toString.call(theObject) [object Array] [object Object]

            function myLittleTest() 
            {
                var obj, arr, armap, i;    

                  // arr is an object and an array
                arr = [1, 2, 3, 5, 7, 11]; 

                obj = {}; // obj is only an object... not an array

                alert (Object.prototype.toString.call(obj));
                  // ^ Output: [object Object]

                obj = arr; // obj is now an array and an object

                alert (Object.prototype.toString.call(arr));
                alert (Object.prototype.toString.call(obj));
                  // ^ Output for both: [object Array]

                // works in IE
                armap = [];
                for(i = 0; i < obj.length; ++i)
                {
                    armap.push(obj[i] * obj[i]);
                }

                alert (armap.join(", ")); 

            }
            // Changed from prueba();
            myLittleTest();