一段讲解使用 JS 实现 OOP 的代码实例

js-oop-example.js

function inheritPrototype(subType, superType) {
	if (Object.create) {
		// 利用 Object.create 的特性实现 __proto__ 指针的正确指向，完美
		subType.prototype = Object.create(superType.prototype);
		subType.prototype.constructor = subType;
	} else {
	    function F() {}
	    F.prototype = superType.prototype;
	    var prototype = new F();
	    prototype.constructor = subType;
	    subType.prototype = prototype;
	}
}

var Employee = (function(){
    var _next_id = 1;
    var _employeeCount = 0;

    function Employee(name, salary, year, month, day) {
        var _this = this;
        var _id = _next_id;

        _this.name = name;
        _this.salary = salary;
        _this.post = "Employee";
        _this.hireDay = new Date(year, month, day);

        _next_id++;
        _employeeCount++;

    }
    
    Employee.prototype.getId = function () {
        return this._id;
    };
    Employee.prototype.setId = function () {
        alert("员工ID由系统自动生成，不能手动修改");
        return false;
    };
    Employee.prototype.computeSeniority = function() {
        return (new Date().getFullYear() - this.hireDay.getFullYear());
    };

    Employee.getNextId = function() {
        return _next_id;
    };
    Employee.setNextId = function(value) {
        alert("Next ID 由系统自动生成，不能手动修改");
        return false;
    };

    Employee.getCounts = function() {
        return _employeeCount;
    };

    return Employee;
})();

var Manager = (function(){

    var _managersCount = 0;

    function Manager(name, salary, year, month, day, bonus) {
        var _this = this;
        Employee.call(_this, name, salary, year, month, day);

        _this.post = "Manager";
        _this.bonus = bonus || 0;

        _managersCount++;
    }

    // 在这里实现继承，而不是在函数外部实现继承，思考为什么？
    inheritPrototype(Manager, Employee);
    
    Manager.prototype.setBonus = function (num) {
        this.bonus = num;
    };

    Manager.getNextId = function() {
        return Employee.getNextId();
    };
    Manager.setNextId = function(value) {
        return Employee.setNextId(value);
    };

    Manager.getCounts = function() {
        return _managersCount;
    };

    return Manager;
})();

// 测试代码
var yangfch3 = new Employee("yangfch3", 1234, 2014, 9, 26);

Employee.getCounts();
Employee.getNextId();
Employee.setNextId(1234);
Object.keys(yangfch3);
yangfch3.getId();
yangfch3.setId(4321);
yangfch3.computeSeniority();
yangfch3.bonus;
yangfch3.setBonus;

var Qu = new Manager("Qu", 12345, 2001, 8, 5, 500);
Manager.getCounts();
Manager.getNextId();
Manager.setNextId(1234);
Object.keys(Qu);
Qu.getId();
Qu.setId(4321);
Qu.computeSeniority();
Qu.bonus;
Qu.setBonus(1111);