Let’s talk in depth about jQuery’s inheritance mechanism

jQuery is a very popular JavaScript library that provides many powerful functions and convenient APIs, making front-end development simpler and more efficient. One of the important concepts is inheritance. Through inheritance, subclasses can inherit the properties and methods of the parent class, thereby reducing the writing of repeated code. So, what kind of inheritance is there in jQuery? This article will provide a comprehensive introduction to jQuery’s inheritance mechanism.

1. Prototypal inheritance

Prototypal inheritance is the most basic inheritance method in JavaScript, and jQuery also uses this method to extend the prototype chain. In jQuery, $ and jQuery are actually the same function, they are both aliases of the jQuery constructor. The jQuery constructor itself is a function object, which has a prototype object prototype, which defines the methods and properties of the jQuery constructor instance.

In jQuery, all DOM elements are obtained through selectors or DOM operations, and they are all extended on a common DOM element base class. The prototype of this DOM element base class is jQuery.prototype, which is the prototype object of the jQuery constructor. All extension methods are defined on this prototype object. When we use jQuery methods, we actually find the corresponding method through this prototype chain.

2. Deep copy inheritance

Deep copy inheritance is a way to completely copy the properties and methods of one object to another object, so that the other object has It has exactly the same properties as the original object. In jQuery, deep copy inheritance is mainly used for extending prototype objects.

Deep copy inheritance in jQuery is implemented by a method called extend(). This method is often called jQuery's extension method, which can combine the properties and methods of two or more objects into a new object and return it.

3. Module inheritance

Module inheritance encapsulates objects and methods in an independent module, so that this module can run independently or become part of other modules . In jQuery, module inheritance is mainly implemented through closures. Each module is an independent function that uses closures to encapsulate internal variables to ensure that they are not visible to the outside world.

A typical jQuery module usually consists of the following parts:

• Define the module namespace
• Execute the module code
• Define the module can Calling API

Module inheritance is widely used in jQuery source code. For example, it is used to create many commonly used jQuery methods, such as Events, Deferreds, and Widgets.

4. Delegated inheritance

Delegated inheritance is a way to delegate some tasks to other objects. In jQuery, delegate inheritance is commonly used for event handling. Due to flaws in the browser event model, event processing is usually delivered through bubbling. This means that the event will eventually be passed to the document object. If we need to handle events on a certain element, we need to implement it through delegate inheritance.

The implementation of delegate inheritance is to bind event handlers through jQuery's on() method. The on() method can bind an event handler to a DOM element, but the handler will only be triggered when the event bubbles to the specified target.

Summary

Inheritance in jQuery is mainly divided into four methods: prototypal inheritance, deep copy inheritance, module inheritance and delegate inheritance. These inheritance methods are implemented through the prototype chain and closure mechanism unique to the JavaScript language. Mastering these inheritance methods can help us better understand jQuery's source code and API, and use jQuery more efficiently for front-end development.

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