JavaScript Performance Hacks | Speed Up Your Code Today | From Slow to Pro: JavaScript Performance Optimization Secrets
In today’s digital world, speed is crucial. Users want web pages and apps to load quickly and run smoothly. Slow websites can frustrate users and make them leave. That’s why it’s important to make sure your JavaScript code is fast and efficient.
JavaScript is a powerful tool for creating interactive web experiences, but it can also slow things down if not used properly. This blog will show you easy tips and tricks to make your JavaScript run faster. We’ll cover simple ways to improve performance, avoid common mistakes, and write better code.
Whether you’re new to JavaScript or have been coding for years, these tips will help you make your web apps faster and more enjoyable for users. Let’s get started and boost your JavaScript performance!
How to speed up your JavaScript code?
Reduce Activity in Loops
Loops are often used in programming.
Each statement in a loop, including the for statement, is executed for each iteration of the loop.
Statements or assignments that can be placed outside the loop will make the loop run faster.
Bad:
for (let i = 0; i < arr.length; i++) {Better Code:
let l = arr.length;
for (let i = 0; i < l; i++) {The bad code accesses the length property of an array each time the loop is iterated.
The better code accesses the length property outside the loop and makes the loop run faster.
Reduce DOM Access
Accessing the HTML DOM is very slow, compared to other JavaScript statements.
If you expect to access a DOM element several times, access it once, and use it as a local variable:
Example
const obj = document.getElementById("demo");
obj.innerHTML = "Hello";Reduce DOM Size
Keep the number of elements in the HTML DOM small.
This will always improve page loading, and speed up rendering (page display), especially on smaller devices.
Every attempt to search the DOM (like getElementsByTagName) will benefit from a smaller DOM.
Avoid Unnecessary Variables
Don’t create new variables if you don’t plan to save values.
Often you can replace code like this:
let fullName = firstName + " " + lastName;
document.getElementById("demo").innerHTML = fullName;With this:
document.getElementById("demo").innerHTML = firstName + " " + lastName;Delay JavaScript Loading
Putting your scripts at the bottom of the page body lets the browser load the page first.
While a script is downloading, the browser will not start any other downloads. In addition all parsing and rendering activity might be blocked.
The HTTP specification defines that browsers should not download more than two components in parallel.
An alternative is to use defer=”true” in the script tag. The defer attribute specifies that the script should be executed after the page has finished parsing, but it only works for external scripts.
If possible, you can add your script to the page by code, after the page has loaded:
Example
<script>
window.onload = function() {
const element = document.createElement("script");
element.src = "myScript.js";
document.body.appendChild(element);
};
</script>Avoid Using with
Avoid using the with keyword. It has a negative effect on speed. It also clutters up JavaScript scopes.
The with keyword is not allowed in strict mode.
Conclusion
Optimizing JavaScript performance is essential for creating fast and responsive web applications. By applying the tips and tricks discussed in this blog, you can significantly improve the speed and efficiency of your code. Remember to avoid common pitfalls, use best practices, and continually monitor and refine your performance.
A fast web experience not only keeps users happy but also enhances your site’s overall success. Keep learning and experimenting with different optimization techniques to stay ahead in the ever-evolving world of web development.
Thank you for reading, and happy coding!
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