JavaScript code: Effective optimization tips to improve performance and website loading time

JavaScript is the ‘king of web development’ that every IT developer knows. In other words, JavaScript offers numerous benefits in the website creating process! However, everything happens for a reason. Likewise, JavaScript does not gain its spot without hardships. Yet, starters may ask, “What is JS?”, “How can it help me?”, “How to make it effective?”,… This article from our ArrowHiTech committed team will answer all of them and even go deeper into our main concern: How to use JavaScript code to improve Javascript performance

After all, anyone loves an attractive and convenient website, right? So why are we hesitating into finding out the key ways to this issue!

We will come to the definition of JavaScript before going to answer the question” How to improve Javascript performance?”

What is JavaScript?

Simply put, JavaScript acts as a programming language that enables features and functions on websites. Certainly, a website does not magically appear there for you to use! For example, integrating maps, 3D models, content updates, etc all comes with the great help of JavaScript.

Today, there are plenty of JS libraries and frameworks to choose from. To sum up, the top 6 most popular ones are Node.JS, React JS, Vue.js, jQuery, EmberJS and AngularJS

Want to know which is more suitable? Read our comparison at:

JavaScript code
Which JS is suitable?

JavaScript benefits

JS undoubtedly brings lots of advantages that help both website developers and users. Yet, there are 5 main big reasons for using it.

  1. Fast UX: it can communicate with servers in the background without front end work.  In short, it saves much time!
  2. Easy UI: above all, JS can simplify the User Interface process and integrate it into websites.
  3. Great responsive Web Design: furthermore, it adapts those web designs into multiple browsers and devices by combining HTML5 and CSS3.
  4. Fast learning: the JavaScript syntax is super flexible, even for starters. In addition, available frameworks and packages help ease the working process.
  5. Global popularity: JS is very well-known in a good way. What’s more, isn’t growing use rate equals high quality product?

Now you’ve seen the main benefits, but what are the simple and effective ways to help better those benefits? Simple, changing JavaScript Codes!

Let’s get started with ways to improve Javascript performance

Top 8 ultimate ways to improve Javascript performance. 

1. Early Loops Breakout

In order to improve Javascript performance, you should consider Early Loops Breakout. You can see that looping consumes much time already, let alone looping for large cycles. Therefore, early breakout comes in handy. Use the ‘break’ and ‘continue’ keywords like the following example.

let arr = new Array(999999999).fill(‘—-‘);

arr[970] = ‘found’;

for (let i = 0; i < arr.length; i++) {

 if (arr[i] === ‘found’) {






let arr = new Array(999999999).fill(‘—-‘);

arr[970] = ‘found’;

for (let i = 0; i < arr.length; i++) {






As a result, that JS code will prevent yours from running the loop 999999999 times!

2. File Compression

JavaScript code file compression
It helps reduce 80% file size!

Compression can reduce file size fairly better than minification, at around 80%. In the end, those JavaScript codes will fasten the web performance and boost productivity. Therefore, you can improve Javascript performance

3. DOM Access Downsize

Normally, DOM access is rather slow. Consequently, changes in DOM will make it slower. However, a simple solution is to access it once then use it as a local variable.

Don’t forget to set it back to ‘null’ when finished because if not, garbage can lead to memory leakage. After all, thanks to DOM Access Downsize, you are able to improve Javascript performance

4. Final Code Minification

To clarify, in order to improve Javascript performance all you need to do is to remove extra spaces in the JavaScript files via online tools and packages As a result, 60% of unnecessary stuff in your file will be gone. Today, it has become a great component for front end optimization. Moreover, minifying JS codes is now the standard practice for any page optimization.

Nonetheless, many are mistaking it with compression. For that reason, you’d better read the next method to avoid mixing up the two ideas!

5. Async and Defer

JavaScript code defer
What are the differences?

Both Defer and Async are the place where you demand the browser to load the script. Yet, the only difference is that Defer takes place after complete rendering while Async doesn’t affect the rendering process. To make it clear, the website content is still displayed because pages do not need to wait for async scripts. By using both attributes in a correct way, it can reduce your page loading time. As a result, you can improve Javascript performance

6. Unused Codes and Features removal

In fact, more JavaScript codes mean more time and work. You must know that not every code helps because they are created for many clients with different needs. To ease the burden, we highly recommend removing the unnecessary codes and features by experts. Because JavaScript codes are connected closely, a minor mistake can lead to extra cost and time to fix. In addition, even worse, your whole website may crash!

To help you save time and cost, we present you this useful article:

Web Development Company: How to find a perfect one for effective sites?

7. Throttle and Debounce

Throttling is the place to define a maximum number when a function is ‘overtime’ while Debouncing specifies the minimum time for a function to work. This article will show many examples that help you understand better!

As a result, these 2 techniques will limit the number of times of handling your event via JavaScript Code.

Using both techniques is the best!

8. Delete Keyword 

Here, we do NOT recommend using the Delete Keyword. Not only do many users claim that it worsens the site performance, delete keyword also makes the JS code work improperly. 

On the other hand, to solve this problem, you can set property into ‘undefined’ instead:

const object = {name:”Jane Doe”, age:43};

object.age = undefined;

9. Hire a Web developer company!

Surprise! This is an optional solution that we highly recommend to improve Javascript performance. Because spending a reasonable amount of money to have the best web performance seems to be a valid investigation. Moreover, you will have more time to take care of any other major issues.

Need urgent help? Hire ArrowHiTech!

ArrowHiTech consistently delivers the most suitable solutions at affordable prices to improve Javascript performance. After working with thousands of clients from the U.S, UK, France to Japan, Singapore and Australia, you will be satisfied when counting on us. Therefore, we are glad to transform your vision into successful reality!

We are the leading IT developers!

ArrowHiTech values every customer, treats them like family and builds relationships on trust. For that reason, we are confident that we can help YOU operate your online stores and deliver the best solutions at an affordable cost. If you have any related issues, feel free to check out our Web App Development Services right now – we welcome customers all the time!


That’s it for today’s topic: JavaScript codes for optimizing website. After all, we hope that you have learned new ideas to adapt to your own. Hopefully, ArrowHiTech will have the chance to help you succeed in your business.