Incorrect Application of Javascript in Your Site is Ruining Your Speed - Templates

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Incorrect Application of Javascript in Your Site is Ruining Your Speed April 17, 2018

Javascript is one of the most effective and versatile programming languages used to achieve an advanced functionality in a website. This programming language has myriad of uses, ranging from bringing on-screen visual effects to collecting information on web pages.

It would not be wrong to say, because of JavaScript we are able to offer a dynamic web experience to our users. Even most of the popular WordPress plugins and themes use this amazing programming language.

Though there are a lot of tasks that are made possible just because of JavaScript yet JavaScript can be one reason your visitors are not able to relish the fast web experience on your site.

It is quite surprising, this amazing front-end programming can slow down your website speed. In fact, any incorrect application of JavaScript (especially those JavaScripts that are served by 3rd party) in your website can ruin speed to a great extent.

How Will You Know If JavaScript is a Problem?

The best way to find out if the JavaScript is actually culprit or not is JavaScript performance test. You can run this test using the tool, You just need to enter your website URL, Test Location, Browser name and hit the ‘Start Test’ button. It is as simple as that.

The result will give you information on each and every JavaScript script or file available on your website.

What Should You Look for in the Performance Test Results

The very first thing you should look for is the number of JavaScript and their total weight. You can look these stats on the ‘Content Complexity’ section available on the results summary page.  If you notice any additional weight of JavaScript, then definitely it is affecting your website speed. Actually, when it comes to JavaScript, the fewer and lighter files is better for you.

If your website has 600 KB or greater JavaScript wight, it can block rendering of the web page, it means your users’ browser will have to load JavaScript before loading rest of the HTML on the page. This whole process can slow-down your web page loading speed.

Most people see eliminating render-blocking JavaScript a good solution to overcome slow speed issue. If you too want to eliminate render-blocking, read out post on how to eliminate render-blocking JavaScript and CSS.

Can JavaScript Optimization Help in Improving Speed?

Yes, the speed improvement is possible by JavaScript optimization. The web page load time can be taken down by 33% through just script magnification and concatenation. JavaScript optimization is more effective than any other speed enhancing techniques.

Let’s take a look at few tips to optimize JavaScript and enhance rendering speed.

Cut Down JavaScript Code for Smaller File Sizes

It is worth mentioning that cutting down JavaScript code is different from obfuscated code. However, both methods are associated with transforming of JavaScript. The minification of JavaScript shrinks the size of files.

Sometimes, small mistakes in JavaScript such as line breaks, additional comments, and space can affect the website speed. By compressing the code you can resolve this issue quite easily. The process will remove all unnecessary characters from the source code without disturbing the functionality.

Dojo ShrinkSafe, Packer and YUI Compressor are few popular JavaScript minification tools.

Make Shortcut Code to Speed Up

One of the most effective ways to improve website speed is creating the shortcuts for useful codes which have been constantly used.

You can write shortcut codes for longer scripts which will save time in the overall process.

Never Use Nested Loops If not Needed

You should avoid unnecessary nested loops, for example, while/for. This way you will be able to keep JavaScript arranged and prevented from going through thousands of objects. Unnecessary loops enforce browser to work harder to process the codes, resulting in slow loading page.

Make Use of .Js file to cache scripts

By using this technique, you can increase your website performance to a great extent. When you use .Js file to cache scripts, it allows your users’ browsers to load the script only once and save all the data to a local drive. This way, when your users will revisit your site, their browsers will recall data from the cache only and will not send requests to the server.

Use HTTP/2

It is the updated version of the HTTP protocol, having some great features such as multiplexing. It means, it can allow multiple requests and provide responses to those requests simultaneously.

If you have not moved to HTTPS yet you’re really missing the benefits of this advanced improvement in HTTP protocol. It really can enhance the performance of your JavaScript and speed up your site.


It is another great practice to improve the performance of your JavaScript. Most website owners are not aware of but the complexity of HTML plays an important role in modifying document objects model objects. By trimming HTML by half, you can double the speed of your DOM.

It can be little tough, but you may start by trimming unnecessary ‘Span’ and ‘Div’ tags.

Compress JavaScript Files

There are plenty of compression options available such as Brotli, Gzip, etc. Use the one you’re comfortable with. By compressing JavaScript, your visitor will be able to download resources faster.

Understand the Importance of Element Load Order

Here, it is important to understand that whenever a user accesses your site, different elements of your site load in his browser.

It is mandatory that all the elements in the ‘Head’ section are preloaded before the user sees anything in his browser. Any JavaScript which is located in the ‘Head’ section can slow down the loading of the page. Make sure your JavaScript is enough optimized otherwise your users will see a white screen before the loading of the page.

Wrapping Up

Undoubtedly, JavaScript is one of the most used and advanced programming languages that you can use to bring endless functionality on your site. However, if it is not optimized properly, it can result in poor website performance. A poorly written JavaScript can give birth to various issues and slow your website to a great extent.

We hope this article will help you avoid some negative effects of JavaScript.

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