Detailed interpretation of the bridging pattern in JavaScript design pattern development (advanced)

The bridge mode is applicable to a wide range of situations. In addition to bridging between event callback functions and interfaces, the bridge mode can also be used to connect public API code and private implementation code. Let’s explain the JavaScript design pattern in detail. The bridge pattern in development uses the

bridge pattern to separate the abstract part from the implementation part so that both can change independently and work harmoniously together. Both the abstract part and the implementation part can be changed independently without affecting each other, which reduces the coupling of the code and improves the scalability of the code.
According to the definition of GoF, the role of the bridge mode is to "isolate abstraction from its implementation so that the two can change independently." This pattern is of great benefit for event-driven programming common in Javascript.

One of the most common and practical applications of the bridge mode is the event listener callback function. Example: Event listener encapsulates event processing statements into callback functions and performs programming through interfaces rather than implementations.

Basic theory

Bridge pattern definition: Separate the abstract part from its implementation part so that they can change independently.
The bridge mode mainly consists of 4 roles:
(1) Abstract class
(2) Extended abstract class
(3) Implementation class interface
(4) Concrete implementation class
According to the characteristics of the JavaScript language, we simplify it into two roles:
(1) Extended abstract class
(2) Concrete implementation class
How to understand the bridge mode? We will next give an example of

implementation of the bridge pattern

The key to understanding the idea of ​​the bridge pattern is to understand its idea of ​​separating the abstract part and the implementation part. Let’s illustrate with an example

The simplest bridge mode

In fact, the each function of jQuery that we most often use is a typical bridge mode. We simulate its implementation as follows:

var each = function (arr, fn) {
  for (var i = 0; i < arr.length; i++) {
    var val = arr[i];
    if (fn.call(val, i, val, arr)) {
      return false;
    }
  }
}
var arr = [1, 2, 3, 4];
each(arr, function (i, v) {
  arr[i] = v * 2;
})

In this example, we loop through the arr array through the each function. Although this example is very common, it contains the typical bridge mode.
In this example, the abstract part is the each function, which is the extended abstract class mentioned above, and the implementation part is fn, which is the concrete implementation class. The abstract part and the implementation part can be changed independently. Although this example is simple, it is a typical bridge mode application.

Bridge mode in plug-in development

One applicable scenario for the bridge mode is component development. We usually develop components to adapt to different occasions, and the components will change in many different dimensions accordingly. The bridge pattern can be applied here, separating its abstraction and implementation, making the component more scalable.
Suppose we want to develop a pop-up window plug-in. There are different types of pop-up windows: ordinary message reminders and error reminders. Each reminder is displayed in a different way. This is a typical multi-dimensional change scenario. First we define two classes: normal message pop-up window and error message pop-up window.

function MessageDialog(animation) {
  this.animation = animation;
}
MessageDialog.prototype.show = function () {
  this.animation.show();
}
function ErrorDialog(animation) {
  this.animation = animation;
}
ErrorDialog.prototype.show = function () {
  this.animation.show();
}

These two classes are the abstract parts mentioned earlier, that is, extended abstract classes. They both contain a member animation.
The two pop-up windows are displayed through the show method, but the animation effects displayed are different. We define two display effect classes as follows:

function LinerAnimation() {
}
LinerAnimation.prototype.show = function () {
  console.log("it is liner");
}
function EaseAnimation() {
}
EaseAnimation.prototype.show = function () {
  console.log("it is ease");
}

These two classes are specific implementation classes, which implement specific display effects. So how do we call it?

var message = new MessageDialog(new LinerAnimation());
message.show();
var error = new ErrorDialog(new EaseAnimation());
error.show();

If we want to add an animation effect, we can define another effect class and pass it in.

Summary

The key to learning the bridge pattern is to understand the separation of the abstract part and the implementation part, so that the two can change independently without being limited to form. The flexible changes of JS plug-ins and the changing applicable scenarios are very suitable for this mode to be implemented. The most important thing about using the bridge pattern is to identify the different dimensions of change in the system.
(1) Advantages of the bridge mode: Isolates abstraction and implementation, which helps to manage each component of the software independently.
(2) Bridge mode disadvantages: Every time a bridge element is used, a function call is added, which will have some negative impact on the performance of the application. Increased system complexity. If a bridge function is used to connect two functions, and one of the functions is never called outside the bridge function, then the bridge function is not necessary at this time.
The bridge pattern "isolates abstraction from implementation so that they can change independently." It promotes code modularity, enables cleaner implementations, and increases abstraction flexibility. It can be used to connect a set of classes and functions together, and provides a means of accessing private data with the help of privileged functions.

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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