Can Web Assembly take over JavaScript?

August 03, 2019

JavaScript has been the base for the majority of the web since last decade. But with the existence of web assembly, it is supposed to take over JavaScript at a fast pace. The properties of web assembly make it a perfect competitor for JavaScript.

What is Web Assembly?

Web Assembly or WASM is a new type of code that runs in the modern web browsers. Web Assemblies is the binaries (or bytecode) produced as a result of compiling the code written by the developer in other languages like C, C++, Dart, .Net etc.
In other words, your website will use WASM to run instead of running completely with JavaScript. JavaScript will still be required on WASM website but only to load the WASM code.

The environment required for Web Assembly

WASM has been standardized for all major browsers supporting it in their latest versions.

The WASM apps run in the browser’s sandboxed environment which makes it safer to run being it a near machine-level code from getting access to other system-specific data. Each browser runs a virtual machine (VM) internally to run the WASM apps.
The older versions of browsers that do not support WASM can also run these apps using asm.js which provides backward compatibility to the Web Assembly applications.

Web Assembly vs JavaScript

WASM has the potential to replace JavaScript as it produces machine-readable (near to machine level) bytecode instead of some minified and uglified JavaScript files. The bytecode is machine-readable i.e. a developer can not reverse engineer your app, unlike a JavaScript app which makes your code safer in terms of logic.

Performance Comparison

The major difference between the two of that:
JavaScript optimizes the code at browser level whereas WASM optimizes the code during compilation, which is a one time process. So WASM code does not need to be optimized when it is loaded into the browser.
Also, since the compiled code (the bytecode) produces *.wasm files which are near to machine level (in binary format), so WASM has a massive advantage of performance over JS.
In the worst case, it can give up to 3x performance gains
In the best case, it can give up to 20x performance gains
With the potential of replacing the JavaScript, let’s see how long will it take to do so.

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