js通过代码来理解构造函数的实现过程

Posted on by mannuan One min read

原生实现

function Person(name){
    this.name = name;
};

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

var a = new Person('sven');
console.log(a.name);
console.log(a.getName());
console.log(Object.getPrototypeOf(a) === Person.prototype);

代码实现

function Person(name){
    this.name = name;
};

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

var objectFactory = function(){
    var obj = new Object(),
        Constructor = [].shift.call(arguments);
    obj.__proto__ = Constructor.prototype;
    var ret = Constructor.apply(obj, arguments);
    
    return typeof ret === "object" ? ret: obj;
}

var a = objectFactory(Person, "sven");
console.log(a.name);
console.log(a.getName());
console.log(Object.getPrototypeOf(a) === Person.prototype);

下面的代码可以实现原生的效果，参考自JavaScript设计模式与开发实践，[p18-p20]