Tips For Writing More Performant Javascript Code

Introduction

Javascript is one of the most popular programming languages for building web applications. However, as applications become more complex, it’s important to ensure that the Javascript code you write is performant, meaning that it executes quickly and efficiently. In this article, we’ll provide some tips for writing more performant Javascript code.

Tip 1: Minimize DOM Manipulation:  DOM (Document Object Model) manipulation can be a performance bottleneck in web applications. When you manipulate the DOM, the browser has to reflow and repaint the page, which can be slow and expensive.

To minimize DOM manipulation, try to make changes to the DOM in batches rather than individually. For example, if you need to add several elements to the page, create a new document fragment, add the elements to it, and then append the fragment to the page. This reduces the number of DOM updates that the browser has to make.

Tip 2: Use Efficient Data Structures: The choice of data structure can have a big impact on the performance of your Javascript code. For example, using an array for a large dataset can be slow because array operations are O(n), meaning that the time it takes to perform an operation increases linearly with the size of the array.

Instead of an array, consider using a Set or a Map, which have O(1) lookup time. This can be especially useful if you need to perform frequent lookups on a large dataset.

Tip 3: Avoid Unnecessary Function Calls: Function calls can be expensive in Javascript, especially if they involve creating new objects or manipulating the DOM. To improve performance, avoid unnecessary function calls.

One way to do this is to cache the results of expensive function calls. For example, if you need to compute the value of a complex expression multiple times, compute it once and store the result in a variable.

Tip 4: Use RequestAnimationFrame for Animations: If you need to animate elements on a web page, use requestAnimationFrame instead of setInterval or setTimeout. requestAnimationFrame is a browser API that allows you to synchronize your animations with the browser’s repaint cycle. This can result in smoother, more performant animations.

Tip 5: Use Event Delegation: Event delegation is a technique for handling events that can improve the performance of your Javascript code. Instead of attaching event listeners to individual elements, you attach a single event listener to a parent element and use event bubbling to handle events on child elements.

This can be more performant because it reduces the number of event listeners that the browser has to manage. Additionally, it can make your code more flexible, since you can add or remove child elements without having to update event listeners.

Tip 6: Use Web Workers: Web Workers are a browser API that allow you to run Javascript code in a separate thread from the main UI thread. This can be useful for computationally intensive tasks that would otherwise block the UI thread and make your application feel unresponsive.

For example, if you need to perform a large computation, you can create a Web Worker to perform the computation in the background while the user interacts with the UI.

Tip 7: Avoid Memory Leaks: Memory leaks can occur in Javascript when objects are created but not properly destroyed, leading to a buildup of unused memory over time. This can eventually cause your application to slow down or crash.

To avoid memory leaks, be sure to properly clean up any objects or event listeners that you create. For example, if you attach an event listener to an element, be sure to detach it when the element is removed from the DOM.

Conclusion