javascrpt 代码复用之继承

参考资料:

《JavaScript 模式》(<< JavaScript Patterns >>)

中国电力出版社。Stoyan Stefanov著， 陈新 译。

 

 

1.原型继承；

var Main = {};

/**
原型继承
prototypal inheitance.
*/
Main.createObj = function(o){
    function F() {};
    F.prototype = o;
    return new F();
};

function Person(pName){
    this.name = pName || "Adam";
};

Person.prototype.getName = function() {
return this.name;
};

Person.prototype.color = "red";

Main.testPrototypal = function(o){
    var papa = new Person();
    var kid = Main.createObj(papa);
    
    console.info(kid.getName());
    console.info("kid-name:" + kid.hasOwnProperty("name"));
    console.info("kid-color:" + kid.hasOwnProperty("color"));
    console.info("kid-getName:" + kid.hasOwnProperty("getName"));
    
    console.info("papa-name:" + papa.hasOwnProperty("name"));// papa-name:true
    console.info("papa-color:" + papa.hasOwnProperty("color"));
    console.info("papa-getName:" + papa.hasOwnProperty("getName"));
};

 

 

2. 通过复制属性实现继承；

2.1 浅复制

/**
复制属性实现继承--浅复制 (shallow copy)

修改子对象会 影响 父对象!!
*/
Main.extend = function(parent, child) {
    var i;
    child = child || {};
    for (i in parent) {
        if (parent.hasOwnProperty(i)) {
            child[i] = parent[i];
        }
    }
    return child;
};

/**
浅复制
*/
Main.testShallowCopy = function(){

console.info(" >>> Main.testShallowCopy");
    var Car = {
        doors: [1,2,3,4],
        energy: {price: "$2.00"}
    };
    
    var oneCar = Main.extend(Car);
    // 修改子对象会 影响 父对象!!
    oneCar.doors.push(9);
    
    // oneCar.doors, 1,2,3,4,9
    console.info("oneCar.doors, " + oneCar.doors.toString());
    // Car.doors, 1,2,3,4,9
    console.info("Car.doors, " + Car.doors.toString());
};

2.2 深度复制 

 

/**
复制属性实现继承--深度复制 (deep copy)

*/
Main.extendDeep = function(parent, child) {
var i,
    toStr = Object.prototype.toString,
    astr = "[object Array]";
    
child = child || {};

for(i in parent) {
    if(parent.hasOwnProperty(i)){
        if(typeof parent[i] === "object"){
            child[i] = (toStr.call(parent[i]) === astr) ? []:{};
            Main.extendDeep(parent[i], child[i]);
        }else{
            child[i] = parent[i];
        }
    }
}
return child;

};


/**
深度复制
*/
Main.testDeepCopy = function(){
    console.info(" >>> Main.testDeepCopy");
    var Car = {
        doors: [5,6,7,8],
        energy: {price: "$2.00"}
    };
    
    var oneCar = Main.extendDeep(Car);
    // 修改子对象 不会影响 父对象!!
    oneCar.doors.push(1);
    
    // oneCar.doors, 5,6,7,8,1
    console.info("oneCar.doors, " + oneCar.doors.toString());
    // Car.doors, 5,6,7,8
    console.info("Car.doors, " + Car.doors.toString());
};