> For the complete documentation index, see [llms.txt](https://javascriptuse.gitbook.io/advanced/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://javascriptuse.gitbook.io/advanced/cach-hoat-dong-cua-cac-module-loader-ok-mot-vi-du-kinh-dien.md).
# Cách hoạt động của các module loader? (ok) một ví dụ kinh điển :)
index.html
```
Loader
```
loader.js
```
(function() {
var libs = new Array;
var styles = new Array;
//Xác định URL của thư viện cần dùng, ở đây tôi dùng WOWjs, sử dụng WOWjs yêu cầu 2 dependencies là jQuery và animate.css
libs[0] = 'https://code.jquery.com/jquery-1.12.4.js';
libs[1] = 'https://cdnjs.cloudflare.com/ajax/libs/wow/1.1.2/wow.js';
styles[0] = 'https://cdnjs.cloudflare.com/ajax/libs/animate.css/3.5.2/animate.min.css';
core = 'main.js';
//Vòng lặp để gửi request thư viện
for (let i = 0; i < libs.length; i++) {
//Sử dụng Promise để xử lý khi có kết quả trả về
libs[i] = new Promise((resolve, reject) => {
let xhttp = new XMLHttpRequest();
xhttp.open("GET", libs[i], true);
xhttp.onload = function() {
//Nếu request tài nguyên thành công, tạo 1 thẻ script và append code vào
if (this.readyState == 4 && this.status == 200) {
let script = document.createElement('script');
script.innerHTML = this.responseText;
let body = document.getElementsByTagName('body')[0];
body.appendChild(script);
resolve();
}
}
xhttp.send();
});
}
for (let i = 0; i < styles.length; i++) {
styles[i] = new Promise((resolve, reject) => {
let xhttp = new XMLHttpRequest();
xhttp.open("GET", styles[i], true);
xhttp.onload = function() {
if (this.readyState == 4 && this.status == 200) {
let style = document.createElement('style');
style.innerHTML = this.responseText;
let body = document.getElementsByTagName('body')[0];
body.appendChild(style);
resolve();
}
}
xhttp.send();
});
}
//Khi tất cả các dependencies đã load xong, thực thi code chương trình
Promise.all(libs.concat(styles)).then(() => {
console.log('Initialized !!!');
let xhttp = new XMLHttpRequest();
xhttp.open("GET", 'main.js', true);
xhttp.onload = function() {
if (this.readyState == 4 && this.status == 200) {
let style = document.createElement('script');
style.innerHTML = this.responseText;
let body = document.getElementsByTagName('body')[0];
body.appendChild(style);
}
}
xhttp.send();
})
})();
```
main.js
```
new WOW().init();
var element = $('body').append('Welcome to Module Loader
');
```
{% file src="/files/-M2zrEvjvH29w59FCAPO" %}
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