js extend 用法

function Parent() {
    this.name = 'Parent';
}

Parent.prototype.sayHello = function() {
    console.log('Hello, I am ' + this.name);
};

function Child() {
    this.name = 'Child';
}

// 使用原型链实现继承
Child.prototype = new Parent();
Child.prototype.constructor = Child;

var child = new Child();
child.sayHello(); // 输出: Hello, I am Child

class Parent {
    constructor() {
        this.name = 'Parent';
    }

    sayHello() {
        console.log('Hello, I am ' + this.name);
    }
}

class Child extends Parent {
    constructor() {
        super();
        this.name = 'Child';
    }
}

const child = new Child();
child.sayHello(); // 输出: Hello, I am Child

var obj1 = { a: 1, b: 2 };
var obj2 = { b: 3, c: 4 };

$.extend(obj1, obj2);

console.log(obj1); // 输出: { a: 1, b: 3, c: 4 }