If you're working on a project using Ruby on Rails and need to optimize the loading of your JavaScript files, adding the "defer" attribute to the `javascript_include_tag` can help improve performance. This simple technique ensures that your scripts are downloaded asynchronously, allowing the rest of your webpage to load without being delayed by the JavaScript files. In this guide, we'll walk you through the steps to add the "defer" attribute to the `javascript_include_tag` in Rails.
The `javascript_include_tag` method in Rails is commonly used to include JavaScript files in your application layout. By default, when you include a JavaScript file using this method, it is loaded synchronously, which means the browser has to wait for the script to download and execute before continuing to render the rest of the page. This can result in slower loading times and a less responsive user experience.
To add the "defer" attribute to the `javascript_include_tag`, you need to make a small modification in your Rails application. Start by locating the layout file where you include your JavaScript files. This is typically the `application.html.erb` file found in the `app/views/layouts` directory of your Rails project.
Inside the layout file, look for the line where you have the `javascript_include_tag` method. It usually looks something like this:
To add the "defer" attribute, you simply need to update the `javascript_include_tag` method as follows:
By adding `, defer: true` at the end of the method call, you are instructing the browser to download the JavaScript file asynchronously. This means that the script will be downloaded in the background while the rest of the page is being rendered, improving the overall loading performance of your application.
It's important to note that the "defer" attribute is supported in modern browsers, so you can safely use it without worrying about compatibility issues. However, if you need to support older browsers, you may want to consider alternative methods or polyfills to achieve similar asynchronous loading behavior.
Once you have added the "defer" attribute to the `javascript_include_tag` in your Rails application, be sure to test your changes to ensure that everything is working as expected. Load your application in a browser and verify that the JavaScript files are being loaded asynchronously without any errors.
In conclusion, adding the "defer" attribute to the `javascript_include_tag` in Rails is a simple yet effective way to improve the loading performance of your application. By following the steps outlined in this guide, you can optimize the delivery of your JavaScript files and provide a faster and more seamless user experience for your visitors.