1、PHP中的 json_encode 函数只限编码UTF-8的数据，当转换GBK或者GB2312等编码的数据时，会将汉字转为NULL。

2、JavaScript 中json 的使用：

dataObj = eval('{"name":"Jack"}'); dataObj = eval('(<?=json_encode(array('name'=>'Jack'))?>)');

④ JQuery中Ajax请求返回JSON的方式：

$.getJSON(url, {param: data}, function (msg){ console.log(msg); });

$.post(url, {param: data}, function (msg){ console.log(msg); }, 'JSON');

3、JavaScript 中，GBK和UTF-8的转换：

资料链接：http://igogogo9.iteye.com/blog/105669

function GB2312UTF8(){this.Dig2Dec=function(s){var retV = 0;if(s.length == 4){for(var i = 0; i < 4; i ++){retV += eval(s.charAt(i)) * Math.pow(2, 3 - i);}return retV;}return -1;} this.Hex2Utf8=function(s){var retS = "";var tempS = "";var ss = "";if(s.length == 16){tempS = "1110" + s.substring(0, 4);tempS += "10" + s.substring(4, 10); tempS += "10" + s.substring(10,16); var sss = "0123456789ABCDEF";for(var i = 0; i < 3; i ++){retS += "%";ss = tempS.substring(i * 8, (eval(i)+1)*8);retS += sss.charAt(this.Dig2Dec(ss.substring(0,4)));retS += sss.charAt(this.Dig2Dec(ss.substring(4,8)));}return retS;}return "";} this.Dec2Dig=function(n1){var s = "";var n2 = 0;for(var i = 0; i < 4; i++){n2 = Math.pow(2,3 - i);if(n1 >= n2){s += '1';n1 = n1 - n2;}elses += '0';}return s;      }this.Str2Hex=function(s){var c = "";var n;var ss = "0123456789ABCDEF";var digS = "";for(var i = 0; i < s.length; i ++){c = s.charAt(i);n = ss.indexOf(c);digS += this.Dec2Dig(eval(n));}return digS;}this.Gb2312ToUtf8=function(s1){var s = escape(s1);var sa = s.split("%");var retV ="";if(sa[0] != ""){retV = sa[0];}for(var i = 1; i < sa.length; i ++){if(sa[i].substring(0,1) == "u"){retV += this.Hex2Utf8(this.Str2Hex(sa[i].substring(1,5)));if(sa[i].length){retV += sa[i].substring(5);}}else{retV += unescape("%" + sa[i]);if(sa[i].length){retV += sa[i].substring(5);}}}return retV;}this.Utf8ToGb2312=function(str1){var substr = "";var a = "";var b = "";var c = "";var i = -1;i = str1.indexOf("%");if(i==-1){return str1;}while(i!= -1){if(i<3){substr = substr + str1.substr(0,i-1);str1 = str1.substr(i+1,str1.length-i);a = str1.substr(0,2);str1 = str1.substr(2,str1.length - 2);if(parseInt("0x" + a) & 0x80 == 0){substr = substr + String.fromCharCode(parseInt("0x" + a));}else if(parseInt("0x" + a) & 0xE0 == 0xC0){ //two byteb = str1.substr(1,2);str1 = str1.substr(3,str1.length - 3);var widechar = (parseInt("0x" + a) & 0x1F) << 6;widechar = widechar | (parseInt("0x" + b) & 0x3F);substr = substr + String.fromCharCode(widechar);}else{b = str1.substr(1,2);str1 = str1.substr(3,str1.length - 3);c = str1.substr(1,2);str1 = str1.substr(3,str1.length - 3);var widechar = (parseInt("0x" + a) & 0x0F) << 12;widechar = widechar | ((parseInt("0x" + b) & 0x3F) << 6);widechar = widechar | (parseInt("0x" + c) & 0x3F);substr = substr + String.fromCharCode(widechar);}}else {substr = substr + str1.substring(0,i);str1= str1.substring(i);}i = str1.indexOf("%");}return substr+str1;}
}