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What this article shares to you is about how to analyze the principle of the new operator. The editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

Front-end interview-the principle of new operator interprets new examples

The new operator in JavaScript is used to create an object instance of a given constructor.

Function Person (name, age) {this.name = name; this.age = age;} const res = new Person ('Tom', 20) console.log (res) / / Person {name: "Tom", age: 20} prototype, constructor, instance relationship

Prototype: a simple object that implements property inheritance of an object. It can be simply understood as the father of the object. In Firefox and Google, each js object contains a * * proto** (non-standard) attribute pointing to its father (the object prototype) that can be accessed by obj.__proto__.

Constructor: you can create a new function for an object through new.

Example: an object created by constructor and new is an instance. The instance points to the prototype through * * proto and to the constructor through constructor**.

Therefore, we can see an example of the relationship between the three. _ _ proto__=== prototype. Constructor = constructor. Prototype = prototype instance. Constructor = constructor new operator implementation principle

Generate a new object

Link to prototype

Bind this

Returns a new object (if the constructor has its own retrun, this value)

Function myNew (constrc,... args) {const obj = {}; / / 1. Create an empty object obj.__proto__ = constrc.prototype; / / 2. Point the [[prototype]] attribute of obj to the prototype object const result = constrc.apply (obj, args) of the constructor; / / 3. Bind the context this executed by constrc to obj and execute return result instanceof Object? Result: obj; / / 4. If the constructor returns an object, the result executed by the constructor is used. Otherwise, return the newly created object} / / example: function Person (name, age) {this.name = name; this.age = age;} const res = myNew (Person, 'Tom', 20) console.log (res) / / Person {name: "Tom", age: 20} is how to analyze the principle of the new operator. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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