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V8.js - Access native v8 engine function from Javascript

gmartigny profile image Guillaume Martigny ・2 min read

When Google decide to create his own web browser, their engineers build a brand new Javascript engine. Build for speed and memory performance, its adoption into Node.js makes it the most influential engine out there.

A few things was impossible to do in Javascript. Specifically discussing with the engine itself and make use of its native methods. Getting a precise measure of the heap memory size (only possible on Chrome), triggering the garbage collector or getting the optimisation status of a function was inaccessible to Javascripts devs.

Not anymore.


Using the flag --allow-natives-syntax on execution now allow you to call all V8's native methods. Since the syntaxe can still be a bit clanky, V8.js wrap it around a more classic library interface.


Like any other library available on NPM, you can install V8.js with one command line:

$ npm install v8.js

Or add a <script> tag in your HTML page:

<script src=""></script>
<!-- Or -->
<script src=""></script>


Once installed, V8.js can be required and expose a list of functions for you to use.

const v8 = require("v8.js"); // Only for node



const v8 = require("v8.js");

const previousUsage = v8.getHeapUsage();
const afterUsage = v8.getHeapUsage();

console.log(`Just cleared ${previousUsage - afterUsage} bytes of memory.`);

I need you !

I still consider it a beta version (hence the v0.2.0 version). So I'll warmly welcome any feedback.

The list of available functions of the v8 engine is quite large and I didn't want to include everything blindly. So if you see something useful V8.js is missing raise a new issue with your use-case.

Peace ✌️

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