how to load external scripts dynamically in angular

When working with Angular, it's often necessary to load external scripts dynamically. This can be especially useful when working with third-party libraries or plugins that need to be loaded on the fly. In this article, we'll discuss how to load external scripts dynamically in Angular and the benefits it provides.

Why Load External Scripts Dynamically?

There are a few reasons why you might want to load external scripts dynamically in Angular. One common reason is to avoid loading unnecessary scripts upfront. By only loading scripts when they are needed, you can reduce the initial load time of your application. Additionally, you may want to load scripts conditionally based on user input or the state of your application. Finally, loading scripts dynamically can help you better manage dependencies and avoid conflicts between different libraries or plugins.

The Basic Approach

The basic approach to loading external scripts dynamically in Angular is to use the script tag. When the script tag is added to the DOM, the browser will automatically load and execute the script. In Angular, we can use the Renderer2 service to dynamically create and insert a script tag into the DOM. Here's an example of how to use Renderer2 to dynamically load an external script:```typescriptimport { Component, OnInit, Renderer2 } from '@angular/core';@Component({ selector: 'app-root', template: ``})export class AppComponent implements OnInit { constructor(private renderer: Renderer2) {} ngOnInit() { const script = this.renderer.createElement('script'); script.src = 'path/to/script.js'; this.renderer.appendChild(document.body, script); }}```Here, we create a new script element using Renderer2's `createElement` method. We then set the `src` attribute of the script element to the path of the script we want to load. Finally, we append the script element to the `document.body` using the Renderer2's `appendChild` method.

Loading Scripts Conditionally

Often, we'll want to load scripts conditionally based on some state in our application. For example, we might want to load a script only when a particular component is displayed on the screen. To do this, we can use a combination of Angular's dependency injection and the Renderer2 service.```typescriptimport { Component, OnInit, Injector, Renderer2 } from '@angular/core';@Component({ selector: 'app-root', template: ``})export class AppComponent implements OnInit { constructor(private injector: Injector, private renderer: Renderer2) {} ngOnInit() { const optionalScript = this.injector.get('optionalScript'); if (optionalScript) { const script = this.renderer.createElement('script'); script.src = 'path/to/script.js'; this.renderer.appendChild(document.body, script); } }}```In this example, we use Angular's Injector service to retrieve a value for the `optionalScript` key. If we've defined a provider for `optionalScript` somewhere in our application, the injector will return that value. Otherwise, it will return `null`.We can then use an if statement to conditionally load the script. If `optionalScript` is truthy, we create a new script element and append it to the DOM using Renderer2 as before.

Conclusion

Dynamically loading external scripts in Angular can be a powerful tool for managing dependencies, improving performance, and providing a better user experience. By using Renderer2 and Angular's dependency injection system, we can dynamically load scripts conditionally and avoid unnecessary script loading. When used correctly, this technique can help make our applications faster, more scalable, and easier to maintain.