js 处理实体字符串

Function.prototype.method=function(name,fun){
    if(!this.prototype[name])
        this.prototype[name]=fun;
}

String.method('deentityify',function(){
    var entity={
        quot:'"',
        lt:'<',
        gt:'>'
    }
    console.log(1);
    return function(){
        return this.replace(/&([^&;]+);/g,function(a,b){
            var ret=entity[b];
            return typeof ret==='string'?ret:a
        })
    }
}());
var str='&lt;&quot;&gt;'
str.deentityify()