方法一：

function clone(obj){  
    var o;  
    if(typeof obj == "object"){  
        if(obj === null){  
            o = null;  
        }else{  
            if(obj instanceof Array){  
                o = [];  
                for(var i = 0, len = obj.length; i < len; i++){  
                    o.push(clone
 
(obj[i]));  
                }  
            }else{  
                o = {};  
                for(var k in obj){  
                    o[k] = clone(obj[k]);  
                }  
            }  
        }  
    }else{  
        o = obj;  
    }  
    return o;  
}  

var obj1 = {name: "kitty", sex: "female"
 
, age: 18, favorite: ["football", "sing", "dancing"]};
var obj2 = clone(obj1);

方法二：

function clone(obj){  
    var o, obj;  
    if (obj.constructor == Object){  
        o = new obj.constructor();   
    }else{  
        o = new obj.constructor(obj.valueOf());   
    }  
    for(var key in obj){  
        if
 
 ( o[key] != obj[key] ){   
            if ( typeof(obj[key]) == 'object' ){   
                o[key] = clone(obj[key]);  
            }else{  
                o[key] = obj[key];  
            }  
        }  
    }  
    o.toString = obj.toString;  
    o.valueOf = obj.valueOf;  
    return o;  
}  

方法三：

function clone(obj){  
    function Fn(){}  
    Fn.prototype = obj;  
    var o = new Fn();  
    for(var a in o){  
        if(typeof o[a] == "object") {  
            o[a] = clone(o[a]);  
        }  
    }  
    return o;  
}