How to load a class dynamically in Javascript ES6

Question

In Javascript ES6, how do we load classes dynamically ?

I'm building an asset manager and in the class 'asset' below there is a load() method that uses the JQuery function $.getScript() to load the file security.js. Nonetheless the file security.js does load as I am able to see the Ajax call and the responses for it. However I am unable to initialize the class by,

neither

yellow = new asset_security();

nor

let script = new window['asset_'+s['screen']]();

My Example:

class asset {
    constructor() {
        this.include = ['general','header','menu'];
        this.css = [];
        this.js = [];


    // Create Defaults for the app
        this.css['general'] = [];
        this.js['general'] = [];

        this.css['header'] = [];
        this.js['header'] = [];

        this.css['menu'] = [];
        this.js['menu'] = [];

//      this.css['general'][this.css['general'].length] = 'initial.css';
//      this.js['general'][this.js['general'].length] = 'controller/initial.js';
//      this.css['header'][this.css['header'].length] = 'header/header.css';
//      this.js['header'][this.js['header'].length] = 'header/controller/header.js';
//      this.css['menu'][this.css['menu'].length] = 'menu/header.css';
//      this.js['menu'][this.js['menu'].length] = 'menu/controller/menu.js';
    }


load() {
    let s = new status(0);
    /**
     * @param data ~ Content of the script returned
     * @param textStatus ~ Verbal response to success or fail
     * @param browser ~ browser.status returns the 200/404/500 statuses
     */
    $.getScript( "/js/asset/"+s['screen']+'.js', function( data, textStatus, browser ) {
        var exist = false;
        try {
            exist = (typeof 'asset_'+s['screen'] === 'function');
        } catch (e) {}
        if ( exist ) {
            //TODO: figure out how to load class dynamically
            /*
            let script = new window['asset_'+s['screen']]();
            script.load();
            script.render();
            */
        }
    });
}

The response that I get from the console state :ReferenceError: asset_security is not defined

What is the proper way to initialize the class after $.getScript() run ?

This is how the asset_security class looks like:

class asset_security extends asset {
    constructor() {
        super();
        this.className = 'asset_security';

        this.include = ['security'];
        this.css['security'] = [];
        this.js['security'] = [];
    }

    load() {
//      this.css['security'][this.css['security'].length] = 'security/formLogin.css';
//      this.js['security'][this.js['security'].length] = 'security/controller/security.js';
//      this.js['security'][this.js['security'].length] = 'security/modal/screen.js';
//      this.js['security'][this.js['security'].length] = 'security/view/screen.js';
    }
}

So you're trying to download a Javascript file then execute it? — Lewis, Apr 12 '16 at 18:45
"*`typeof 'asset_'+s['screen'] === 'function'`*" - huh? How can concatenating a string to anything yield a function? That can't work in ES5 either. — Bergi, Jun 25 '16 at 22:09
possible duplicate of [Create object from string in JavasScript ECMAScript 6](http://stackoverflow.com/q/31776949/1048572) — Bergi, Jun 25 '16 at 22:11

score 0 · Answer 1 · answered May 01 '19 at 13:32

I see that you're trying to load a JavaScript file after downloading it from some external resource. You can create a script tag and load your JavaScript class file through it.

Example:

if ( file_exists ) {
   var imported = document.createElement('script');
   imported.src = '/path/to/imported/script';
   document.head.appendChild(imported);
}

How to load a class dynamically in Javascript ES6

1 Answers1