IE6,7,8中JSON.stringify问题

个人喜欢用JS对象赋值，然后转换成JSON数组，Ajax提交到后台。

个人代码如下:

<span style="font-size:14px;">var jsonObj = {};
jsonObj.username = "zhangsan";
jsonObj.age = 13;

var json = JSON.stringify(jsonObj);
$.ajax(
{
	url:'xxx',
	data:json,
	dataType:'json',
	type:'POST',
	contentType:'application/json;charset=UTF-8',
	success:function(data)
	{
		
	}
})</span>

默认的JSON对象在IE6，7，8中并不支持，所以我选择导入一个外部JSON；
json.js地址：http://download.csdn.net/download/wow4464/7840187
其实代码不长，如下：(此js重新定义了一个JSON对象，并封装了stringify方法)

<span style="font-size:14px;">if (typeof JSON !== 'object') 
{
    JSON = {};
}

(function () 
{
    'use strict';
    function f(n)
    {
        return n < 10 ? '0' + n : n;
    }

    if (typeof Date.prototype.toJSON !== 'function')
    {
        Date.prototype.toJSON = function () 
        {
            return isFinite(this.valueOf())
                ? this.getUTCFullYear()     + '-' +
                    f(this.getUTCMonth() + 1) + '-' +
                    f(this.getUTCDate())      + 'T' +
                    f(this.getUTCHours())     + ':' +
                    f(this.getUTCMinutes())   + ':' +
                    f(this.getUTCSeconds())   + 'Z'
                : null;
        };

        String.prototype.toJSON      =
        Number.prototype.toJSON  =
        Boolean.prototype.toJSON = function ()
        {
             return this.valueOf();
        };
    }

    var cx,
        escapable,
        gap,
        indent,
        meta,
        rep;


    function quote(string) 
    {
        escapable.lastIndex = 0;
        return escapable.test(string) ? '"' + string.replace(escapable, function (a)
        {
            var c = meta[a];
            return typeof c === 'string'
                ? c
                : '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
        }) + '"' : '"' + string + '"';
    }
    function str(key, holder) 
    {
        var i,          
            k,          
            v,         
            length,
            mind = gap,
            partial,
            value = holder[key];

        if (value && typeof value === 'object' &&
                typeof value.toJSON === 'function') 
        {
            value = value.toJSON(key);
        }

        if (typeof rep === 'function')
        {
            value = rep.call(holder, key, value);
        }

        switch (typeof value) 
        {
        case 'string':
            return quote(value);

        case 'number':

            return isFinite(value) ? String(value) : 'null';

        case 'boolean':
        case 'null':

            return String(value);

        case 'object':

            if (!value) {
                return 'null';
            }

            gap += indent;
            partial = [];

            if (Object.prototype.toString.apply(value) === '[object Array]') {

                length = value.length;
                for (i = 0; i < length; i += 1)
                {
                    partial[i] = str(i, value) || 'null';
                }

                v = partial.length === 0
                    ? '[]'
                    : gap
                    ? '[\n' + gap + partial.join(',\n' + gap) + '\n' + mind + ']'
                    : '[' + partial.join(',') + ']';
                gap = mind;
                return v;
            }

            if (rep && typeof rep === 'object') 
            {
                length = rep.length;
                for (i = 0; i < length; i += 1) 
                {
                    if (typeof rep[i] === 'string') 
                    {
                        k = rep[i];
                        v = str(k, value);
                        if (v) 
                        {
                            partial.push(quote(k) + (gap ? ': ' : ':') + v);
                        }
                    }
                }
            } 
	        else 
	        {
	
	             for (k in value) 
	             {
	                 if (Object.prototype.hasOwnProperty.call(value, k))
	                 {
	                	 v = str(k, value);
		                 if (v) 
		                {
		                      partial.push(quote(k) + (gap ? ': ' : ':') + v);
		                }
	                 }
	             }
	        }

            v = partial.length === 0
                ? '{}'
                : gap
                ? '{\n' + gap + partial.join(',\n' + gap) + '\n' + mind + '}'
                : '{' + partial.join(',') + '}';
            gap = mind;
            return v;
        }
    }

    if (typeof JSON.stringify !== 'function') 
    {
        escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
        meta =
        {    // table of character substitutions
            '\b': '\\b',
            '\t': '\\t',
            '\n': '\\n',
            '\f': '\\f',
            '\r': '\\r',
            '"' : '\\"',
            '\\': '\\\\'
        };
        JSON.stringify = function (value, replacer, space) 
        {

            var i;
            gap = '';
            indent = '';
            if (typeof space === 'number') 
            {
                for (i = 0; i < space; i += 1) 
                {
                    indent += ' ';
                }

            } 
            else if (typeof space === 'string') 
            {
                indent = space;
            }

            rep = replacer;
            if (replacer && typeof replacer !== 'function' &&
                    (typeof replacer !== 'object' ||
                    typeof replacer.length !== 'number'))
            {
                throw new Error('JSON.stringify');
            }

            return str('', {'': value});
        };
    }

    if (typeof JSON.parse !== 'function')
    {
        cx = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
        JSON.parse = function (text, reviver)
        {
            var j;

            function walk(holder, key) 
            {
                var k, v, value = holder[key];
                if (value && typeof value === 'object') 
                {
                    for (k in value) {
                        if (Object.prototype.hasOwnProperty.call(value, k))
                        {
                            v = walk(value, k);
                            if (v !== undefined) 
                            {
                                value[k] = v;
                            } else
                            {
                                delete value[k];
                            }
                        }
                    }
                }
                return reviver.call(holder, key, value);
            }

            text = String(text);
            cx.lastIndex = 0;
            if (cx.test(text))
            {
                text = text.replace(cx, function (a)
                {
                    return '\\u' +
                        ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
                });
            }


            if (/^[\],:{}\s]*$/
                    .test(text.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, '@')
                        .replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']')
                        .replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {

                j = eval('(' + text + ')');

                return typeof reviver === 'function'
                    ? walk({'': j}, '')
                    : j;
            }

            throw new SyntaxError('JSON.parse');
        };
    }
}());
</span>