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This article mainly explains "what are the methods of JavaScript performance optimization". The content of the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the methods of JavaScript performance optimization".

Typical js performance Challen

There are many factors that affect the performance of JavaScript. The following are common questions related to js performance:

Poor event handling quality:

Proper use of event handlers can improve the performance of JavaScript by reducing the depth of the call stack.

It is important to track all event handlers so that handlers do not execute without your knowledge.

Unorganized code

JavaScript is loose, which has both advantages and disadvantages.

The molecular set of lexical constructs allows developers to implement many functions. However, a lack of organization in the code can lead to underallocation of resources.

This greatly hinders the performance of JavaScript. Understanding ECMA is very important for understanding JavaScript.

Too much dependence.

Sometimes JavaScript dependencies are poorly managed or overmanaged. When this happens, the performance of the application will be adversely affected.

For example, mobile users with limited bandwidth will have to wait longer to render objects.

Inefficient iteration

The iterative process takes a long time. However, it is also beneficial. The long processing time creates a perfect starting point for JavaScript optimization. When you fix irrelevant calls or loops in your code, your JavaScript performance will be greatly improved.

Recommendations for js performance optimization

Pruning HTML

JavaScript HTML is complex and plays a vital role in querying time, querying, and modifying DOM objects.

When you cut the HTML of an application in half, the speed of DOM may double. This may be difficult, but it is possible by discarding tags like and.

Batch DOM changes

Batch DOM conversion to prevent repeated screen rendering. When you create style changes, you make all the changes at once, rather than applying them individually to each style.

Learning the method of Asynchronous programming

JavaScript applications need to make multiple internal calls to a large number of api to get data.

Each function requires middleware because JavaScript is single-threaded.

Synchronization components sometimes lock the entire application. JavaScript uses async.js to manage asynchronous code.

Asynchronous code does not block threads. Instead, the threat is jammed into the event queue, which is triggered after other code is executed.

Using the JavaScript asynchronous feature, you may inadvertently take advantage of external libraries to recover asynchronous interference calls.

This degrades the performance of JavaScript. Instead, you should use asynchronous api in your code, especially in critical performance parts.

Use gzip Compression

JavaScript files can be very large. Use GZip to extract and compress files. GZip reduces latency, improves application performance, and saves bandwidth. With GZip, the server compresses the resource before sending it to the browser.

Using HTTP / 2

The latest version of HTTP is HTTP/2, which improves the performance of JavaScript and speeds up the performance of the website.

HTTP/2 uses multiplexing to allow multiple responses and requests to be sent at the same time.

Buffer DOM

If you have scrollable div, you can use a buffer to clear DOM entries that are currently not visible in viewports. These techniques save DOM traversal and memory usage.

Restricted library dependency

Load time affects the dependencies of the library, so it is important to keep utilization to a minimum.

The best way to take advantage of external library dependencies is to rely on in-browser technologies.

When using the CSS selector, use Sizzle.js instead of jQuery. When the library contains a single feature, it is critical to add a separate CSS selector.

Keep the code lightweight

Keeping the JavaScript code compact will reduce latency and improve performance. When optimizing JavaScript performance, ask yourself:

Is there a real need for this module?

What are the reasons for using this framework?

Is it worth the cost?

Is there an easier way?

Optimize JavaScript performance by converting multiple JS files into one.

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