做前端我们经常要用到JSON.stringify来将JSON转成字符串，但悲剧的是IE6与IE7并不支持JSON.stringify。下面我们来简单讲一下如何解决IE6 IE7 JSON.stringify JSON 未定义问题。

首先我们需要引入一个json2.js的文件(请在本文下方下载)，如果你不想引用一个文件这么麻烦。可以将以下压缩好的代码添加至你的JS文件中（注意代码位置必须靠前）

"object"!=typeof JSON&&(JSON={}),function(){"use strict";function f(a){return 10>a?"0"+a:a}function quote(a){return escapable.lastIndex=0,escapable.test(a)?'"'+a.replace(escapable,function(a){var b=meta[a];return"string"==typeof b?b:"\\u"+("0000"+a.charCodeAt(0).toString(16)).slice(-4)})+'"':'"'+a+'"'}function str(a,b){var c,d,e,f,h,g=gap,i=b[a];switch(i&&"object"==typeof i&&"function"==typeof i.toJSON&&(i=i.toJSON(a)),"function"==typeof rep&&(i=rep.call(b,a,i)),typeof i){case"string":return quote(i);case"number":return isFinite(i)?String(i):"null";case"boolean":case"null":return String(i);case"object":if(!i)return"null";if(gap+=indent,h=[],"[object Array]"===Object.prototype.toString.apply(i)){for(f=i.length,c=0;f>c;c+=1)h[c]=str(c,i)||"null";return e=0===h.length?"[]":gap?"[\n"+gap+h.join(",\n"+gap)+"\n"+g+"]":"["+h.join(",")+"]",gap=g,e}if(rep&&"object"==typeof rep)for(f=rep.length,c=0;f>c;c+=1)"string"==typeof rep[c]&&(d=rep[c],e=str(d,i),e&&h.push(quote(d)+(gap?": ":":")+e));else for(d in i)Object.prototype.hasOwnProperty.call(i,d)&&(e=str(d,i),e&&h.push(quote(d)+(gap?": ":":")+e));return e=0===h.length?"{}":gap?"{\n"+gap+h.join(",\n"+gap)+"\n"+g+"}":"{"+h.join(",")+"}",gap=g,e}}"function"!=typeof Date.prototype.toJSON&&(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"!=typeof JSON.stringify&&(escapable=/[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,meta={"\b":"\\b"," ":"\\t","\n":"\\n","\f":"\\f","\r":"\\r",'"':'\\"',"\\":"\\\\"},JSON.stringify=function(a,b,c){var d;if(gap="",indent="","number"==typeof c)for(d=0;c>d;d+=1)indent+=" ";else"string"==typeof c&&(indent=c);if(rep=b,b&&"function"!=typeof b&&("object"!=typeof b||"number"!=typeof b.length))throw new Error("JSON.stringify");return str("",{"":a})}),"function"!=typeof JSON.parse&&(cx=/[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,JSON.parse=function(text,reviver){function walk(a,b){var c,d,e=a[b];if(e&&"object"==typeof e)for(c in e)Object.prototype.hasOwnProperty.call(e,c)&&(d=walk(e,c),void 0!==d?e[c]=d:delete e[c]);return reviver.call(a,b,e)}var j;if(text=String(text),cx.lastIndex=0,cx.test(text)&&(text=text.replace(cx,function(a){return"\\u"+("0000"+a.charCodeAt(0).toString(16)).slice(-4)})),/^[\],:{}\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,"")))return j=eval("("+text+")"),"function"==typeof reviver?walk({"":j},""):j;throw new SyntaxError("JSON.parse")})}();

在HTML代码中我们也可以使用以下来代码节约流量（IE7+及其它浏览器不加载json2.js）

<!--[if lt IE 8 ]><script src="json2.js"></script><![endif]-->