Contents
If you’re concerned about your website’s loading speed, you may have heard that you should defer parsing of JavaScript. But what does that mean, and how do you do it? This blog post will explain everything you need to know about deferring parsing of JavaScript, so you can make your website as fast as possible!
Checkout this video:
Introduction: Why defer parsing of JavaScript?
JavaScript is a programming language that allows web developers to add interactive features to their websites. However, JavaScript can also slow down your website if it is not properly optimized. One way to optimize JavaScript is to defer parsing of JavaScript.
Parsing is the process of converting code from one form to another. In the case of JavaScript, parsing is the process of converting the code from human-readable form to computer-readable form. When a browser parses JavaScript, it has to pause everything else it is doing in order to understand the code. This can slow down your website, especially if your JavaScript code is large or complex.
Deferring parsing of JavaScript means that the browser will not parse the code until after the page has loaded. This can improve performance because the browser can continue loading other resources (such as images) while it is still parsing the JavaScript code.
It is important to note that not all browsers support deferring parsing of JavaScript. In addition, some browsers may have bugs that prevent deferring from working properly. For these reasons, you should always test your website in multiple browsers before making any changes.
What is JavaScript?
JavaScript is a programming language that is used to make web pages interactive. It is often used to create various forms of interactivity on a page, such as rollover effects, drop-down menus, and popup windows.
What is Parsing?
Parsing is the process of turning a string of characters into a data structure that a computer can understand. JavaScript parsing is usually done by the browser, and it is the browser’s responsibility to turn the JavaScript code into something that can be run on the website.
When a browser loads a website, it has to parse all the HTML, CSS, and JavaScript on the page. This can be a time-consuming process, especially if there is a lot of code to parse. If there is too much code to parse, it can slow down the page loading process.
One way to improve the performance of a website is to defer parsing of JavaScript. Deferring parsing means that the browser doesn’t start parsing the JavaScript code until after it has finished loading the HTML and CSS. This means that there is less work for the browser to do at once, and it can load the page faster.
To defer parsing of JavaScript, you can use the async or defer attributes on your
How can JavaScript be Deferred?
JavaScript can be deferred in order to improve loading times of web pages. When JavaScript is deferred, it is not loaded immediately when the page loads. Instead, it is loaded at a later time, after other elements of the page have been loaded. This can be beneficial because it reduces the amount of time that visitors have to wait for the page to load.
There are several ways to defer parsing of JavaScript. One way is to use the async attribute. The async attribute tells the browser that it can continue to load other parts of the page while the JavaScript file is being downloaded. This can improve loading times because visitors do not have to wait for the JavaScript file to finish downloading before they can see other parts of the page.
Another way to defer parsing of JavaScript is to use a defer attribute. The defer attribute tells the browser to wait until the entire page has been loaded before it starts loading the JavaScript file. This can be beneficial because it ensures that visitors will not have to wait for the JavaScript file to finish downloading before they can see other parts of the page.
A third way to defer parsing of JavaScript is to use a script tag with a src attribute. The src attribute specifies the URL of the JavaScript file that should be downloaded. The script tag also has a type attribute, which specifies that the script should be treated as JavaScript. The async and defer attributes can also be used with script tags.
In order for deferred parsing of JavaScript to work, browsers must support either the async or defer attributes, or both.
What are the Benefits of Deferring JavaScript?
There are several benefits to deferring parsing of JavaScript:
1.improved page load time
2.reduced CPU usage
3.reduced memory usage
4.reduced overall resource usage
Deferring parsing of JavaScript can improve page load time because it allows the browser to continue loading and rendering the page while the JavaScript file is being downloaded. This can be particularly beneficial on slow networks or devices with limited resources.
Deferring also reduces CPU usage because the browser can parse and execute the JavaScript only when it needs to, instead of all at once when the page loads. This can lead to improved performance on devices with limited processing power, such as smartphones or tablets.
Finally, deferring parsing of JavaScript can reduce memory usage because the browser doesn't have to keep all of the JavaScript code in memory while it's loading the page. This can free up resources for other tasks and improve overall performance.
How to Implement Deferred JavaScript?
JavaScript is a powerful tool that can make web pages more interactive and responsive. However, JavaScript can also slow down web page loading times if it is not used carefully.
One way to improve the loading time of a web page is to defer parsing of JavaScript until after the page has finished loading. By deferring parsing of JavaScript, the browser can continue to load other resources (such as images) while the JavaScript code is parsed.
There are several ways to implement deferred JavaScript:
1. Use the async attribute:
The async attribute allows the browser to continue loading other resources while the JavaScript code is parsed. The async attribute can be added to the
2. Use the defer attribute:
The defer attribute allows the browser to continue loading other resources while the JavaScript code is parsed. The defer attribute can be added to the
3. Use an IIFE: An IIFE (Immediately Invoked Function Expression) is a function that is immediately executed when it is created. By wrapping your JavaScript code in an IIFE, you can ensure that it will not be executed until after the page has finished loading:
(function() {
// Your JavaScript code goes here
})();
Conclusion
In conclusion, it is important to Defer Parsing of JavaScript in order to improve the loading speed of your website. By doing so, you will ensure that the most important content is loaded first, and that less important content is loaded last. This will improve the user experience on your website, as well as the overall performance of your site.
References
-http://www.feedthebot.com/pagespeed/defer-loading-javascript.html
-https://developers.google.com/speed/docs/insights/BlockingJS
