How to Dynamically Load External Scripts in Angular?

Dynamically Loading External Scripts in Angular

You may encounter scenarios where you need to seamlessly integrate external libraries into your Angular application without explicitly adding tags in the index.html file. This article addresses this specific need by delving into a step-by-step guide to dynamically loading external scripts in Angular.

Using the Angular Service

We introduce a dedicated Angular service to handle script loading efficiently. This service, ScriptService, manages a registry of scripts to be loaded, with each script identified by a name and accompanied by its source path (CDN or local). When requested, the service fetches the script, ensuring that it is loaded only once to prevent duplication.

Implementing the Service

The implementation of ScriptService involves creating an array of scripts to store the name-src pair of all external scripts. For each script, the service maintains a loaded flag to avoid redundant loading. Upon initialization, it preloads the scripts listed in the array.

The service's load() method accepts an array of script names to be loaded. It iterates through the names, triggering the loadScript() method for each.

The loadScript() method checks if the script has already been loaded by inspecting the loaded flag. If loaded, it immediately resolves the promise.

For scripts that need to be loaded, loadScript() dynamically creates a element, sets its source to the specified path, and manages its loading status using event listeners on readystatechange (IE) or onload (others). On successful script execution, it updates the loaded flag and resolves the promise with information about the script.

Integrating the Service

To utilize ScriptService, simply inject it into the component where you need to load external scripts. Then, use the load() method, passing in the name of the scripts to be loaded. The promise returned by load() can be handled to perform any necessary operations after the script has been loaded.

Example Usage

Here's a snippet demonstrating how to use ScriptService in your component:

@Component({ selector: 'my-component', template: ` Component Template `, }) export class MyComponent { constructor(private scriptService: ScriptService) {}

ngOnInit() { this.scriptService.load('filepicker', 'rangeSlider').then(data => { console.log('Scripts loaded successfully', data); }).catch(error => { console.log('Error loading scripts', error); }); } } By leveraging ScriptService, you can effortlessly load external scripts dynamically in your Angular application, ensuring that scripts are only included when necessary, optimizing the performance and flexibility of your app.