Dynamic imports in JavaScript allow you to load code asynchronously and on-demand, instead of including it all at once when the page loads. This can improve the performance of a web application by reducing the amount of code that needs to be downloaded and parsed upfront.
Dynamic imports are typically used to load code that is only required for certain parts of an application or in response to specific events. To use dynamic imports, you create a JavaScript module with the import statement inside it, and then export the module using the export default syntax:
const myModule = () => {
// code goes here
};
export default myModule;
To import this module dynamically, you use the import() function asynchronously and assign it to a variable:
import myModule from './myModule';
// usage of myModule
The myModule variable will only be assigned a value once the module has finished loading, which may take some time. In the meantime, the rest of your code can continue executing without waiting for the module to load.
Here's an example of how you might use dynamic imports in a web application:
// main.js
import myModule from './myModule';
// usage of myModule
// lazy-load.js
export default function() {
return import('./myModule');
}
// index.html
<script src="lazy-load.js"></script>
In this example, we're using the import statement to load a module asynchronously and on-demand. The lazy-load.js file exports a function that returns the promise returned by the import() function, which is then used in the HTML file to load the module only when it is needed.