克隆函数

function clone(obj){
    var o;
    switch (typeof obj){
        case "undefined":
            break;
        case "string":o=obj+"";
            break;
        case "number":o=obj-0;
            break;
        case "boolean":o=obj;
            break;
        case "object":{
            if(obj===null){
                o=null;
            }else{
                if (Object.prototype.toString.call(obj).slice(8,-1)==="array"){
                    o=[];
                    for(var i=0;i<obj.length;i++){
                        o.push(clone(obj[i]))
                    }
                }else{
                    o={};
                    for(var key in obj){
                        o[key]=clone(obj[key])
                    }
                }
            }
        }
            break;
        default :o=obj;
            break;
    }
    return o;
}