What is the principle of JavaScript proxy mode?

In JavaScript, the principle of the proxy mode is to provide a substitute or occupier for an object to control access to it; by providing a proxy for an object, the proxy object controls access to the original object. Reference is an object structure pattern.

The operating environment of this tutorial: Windows 10 system, JavaScript version 1.8.5, Dell G3 computer.

What is the principle of JavaScript's proxy mode

A proxy is an object (proxy) used to control access to the target object. For this purpose, it must first have the same interface as the target object, but it is different from the decorator pattern in that it does not make any modifications to the target object. Its purpose is to delay the initialization time of "complex" objects. This way you can initialize the target object when it is used (especially important for singletons).

Provide a substitute or placeholder for an object to control access to it

Provide a proxy for an object, and the proxy object controls the reference to the original object. The proxy mode is an object structure mode

The proxy mode has two categories:

(1) Ordinary proxy

(2) Lazy proxy

Look at a piece of code:

function getSomething(value) {
    if (value > 10) {
        return value * 2;
    }
}

Here we define a function. If the value passed in is greater than 10, then we return 2 times its value. Um. . . It's pretty good, but it has its shortcomings. The function does too many things. Our purpose is to obtain twice the value of the parameter, and we make a conditional judgment here. (Of course it doesn't have any impact here, I'm just giving a simple example) The function we want is just to return a value.

Looking at a piece of code:

function getSomething(value) {
    return value * 2;
}
function proxtGet(value) {
    if (value <10) return;
    return getSomething(value);
}

Now we have separated the function of getSomething and judged to use proxyGet to do it, then getSomething can do its own thing safely.

In fact, it is a kind of protection proxy. We provide the proxyGet method to protect the target object. Only those who meet the conditions can operate it.

If one day there is no need to make a judgment, then we can directly call getSomething to get the result. It is very convenient.

The following is an introduction to virtual agents:

In web development, the most expensive thing is undoubtedly the network request. Suppose we have a list, which represents the background file information. We click on a list and it will To send a request to package files to the background, for you who have a Kirin Arm, such network overhead is a nightmare (assuming that the real-time requirements of this operation are not very high), then we can operate like this to reduce Small overhead:

function sendFile(files) {
    // 做一些操作，然后发送文件信息给后台
    console.log('发送成功');
}
var  proxySendFile = (function () {
    var caches = [];
    var timer = null;
    return function (file) {
        caches.push(file);
        if (timer) { return };
        timer = setTimeout(function () {
            sendFile(caches);
            clearInterval(timer);
            timer = null;
            caches.length = 0;
        }, 2000)
    }
}
)()

Here sendFile is the operation of sending files. We use proxySendFIle to proxy the operation of sending files. Only one request is initiated in 2000. Do you think it is possible? Even if your Qilin Arm is unstoppable, there is no difference between you and others here.

Related recommendations: javascript learning tutorial

The above is the detailed content of What is the principle of JavaScript proxy mode?. For more information, please follow other related articles on the PHP Chinese website!