JavaScript中创建对象的几种模式

 1 function createPerson(name, age, job) {
 2     var o = new Object();
 3     o.name = name;
 4     o.age = age;
 5     o.job = job;
 6     o.sayName = function() {
 7         return this.name;
 8     };
 9     return o;
10 }

function Person(name, age, job) {
    this.name = name;
    this.age = age;
    this.job = job;
    this.sayName = function() {
        alert(this.name);
    };
}

var person1 = new Person("Nicholas", 29, "Software Engineer");
var person2 = new Person("Greg", 27, "Doctor");

alert(person1.constructor == Person);
alert(person2.constructor == Person);
alert(person1 instanceof Object);
alert(person1 instanceof Person);
alert(person2 instanceof Object);
alert(person2 instanceof Person);

//当作构造函数使用
var person = new Person("Nicholas", 29, "Software Engineer");
person.sayName();

//当作普通函数使用
Person("Greg", 27, "Doctor");
window.sayName();

//在另一个对象的作用域中调用
var o = new Object();
Person.call(o, "Kristen", 25, "Nurse");
o.sayName();

function Person() {
}

Person.prototype.name = "Nicholas";
Person.prototype.age = 29;
Person.prototype.job = "Software Engineer";
Person.prototype.sayName = function() {
    alert(this.name);
};

var person1 = new Person();
person1.sayName();

var person2 = new Person();
person2.sayName();

alert(person1.sayName == person2.sayName);

//alert(Person.prototype.isPrototypeOf(person1));
//alert(Person.prototype.isPrototypeOf(person2));

alert(Object.getPrototypeOf(person1) == Person.prototype);
alert(Object.getPrototypeOf(person1).name);

function hasPrototypeProperty(object, name) {
    return !hasOwnProperty(name) && (name in object);
}

var person = new Person();
alert(hasPrototypeProperty(person, "name"));

person.name = "Greg";
alert(hasPrototypeProperty(person, "name"));


var keys = Object.getOwnPropertyNames(Person.prototype);
alert(keys);


//更简单的原型语法:此时constructor属性不再指向Person

function Person() {
};

Person.prototype = {
    name : "Nicholas",
    age : 29,
    job : "Software Engineer",
    sayName : function() {
        alert(this.name);
    }
};

var friend = new Person();

Person.prototype.sayHi = function() {
    alert("Hi");
};

friend.sayHi();

function Person() {
};

Person.prototype = {
    constructor : Person,
    name : "Nicholas",
    age : 29,
    job : "Software Engineer",
    friends : ["Shelby", "Court"],
    sayName : function() {
        alert(this.name);
    }
};

var person1 = new Person();
var person2 = new Person();

person1.friends.push("Van");

alert(person1.friends);
alert(person2.friends);
alert(person1.friends === person2.friends);

//动态原型模式
function Person(name, age, job){

    //属性
    this.name = name;
    this.age = age;
    this.job = job;
    this.friends = ["Shelby", "Court"];

    //方法
    if (typeof this.sayName != "function"){

        Person.prototype.sayName = function() {
            alert(this.name);
        };
    }
}

Person.prototype = {
    constructor : Person,
    sayName : function(){
        alert(this.name);
    }
}

var person1 = new Person("Nicholas", 29, "Software Engineer");
var person2 = new Person("Greg", 27, "Doctor");

person1.friends.push("Van");
alert(person1.friends);
alert(person2.friends);
alert(person1.friends === person2.friends);
alert(person1.sayName === person2.sayName);

/*寄生构造函数模型*/
function Person(name, age, job){
    var o = new Object();
    o.name = name;
    o.age = age;
    o.job = job;
    o.sayName = function(){
        alert(this.name);
    };
    return o;
}

var friend = new Person("Nicholas", 29, "Software Engineer");
friend.sayName();

function SpecialArray(){
    var values = new Array();
    values.push.apply(values, arguments);
    values.toPipedString = function() {
        return this.join("|");
    };

    return values;
}

var colors = new SpecialArray("red", "blue", "green");
alert(colors.toPipedString());