The following are some issues with the new operator. This article will explain the relevant issues.
Look at the results first
function Person (name, age, job) { this.name = name this.age = age this.job = job } Person.prototype.sayName = function () { console.log(this.name) }// 使用new操作符var p1 = new Person('laoyang', '22', 'coding') p1 instanceof Person // true// 不使用new 操作符var p2 = new Object() Person.call(p2, 'xiaoyang', '2', 'test') p2.__proto__ = Person.prototype p2 instanceof Person // true
Compare the differences
// 使用new 操作符直接创建实例var p1 = new Person('laoyang', '22', 'coding') // 不使用new 操作符var p2 = new Object() // p2 创建成为一个对象 这时p2的原型是ObjectPerson.call(p2, 'xiaoyang', '2', 'test') // Person构造函数在 p2 对象的环境内执行 这时p2已经是一个具有Person属性的实例了,但原型是Objectp2.__proto__ = Person.prototype // 最后把Person.prototype 赋值给p2.__proto__,让p2的原型指向Person.prototype
Steps to create an instance without using the new operator:
Person.call(p2, 'xiaoyang', '2', 'test') // d
This article shows issues related to the new operator. For more related issues, please pay attention to the PHP Chinese website.
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