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The use of JavaScript engines is not limited to browsers. For example, the V8 engine is a core component of the Node.js and Deno runtime systems. A sizable portion of the Hackaday audience groans and runs their eyes when some new-fangled Javascript thing comes out. Bun is a runtime t that offers a performant all-in-one approach.
In a browser, the JavaScript engine runs in concert with the rendering engine via the Document Object Model. Deno ships as a single executable with no dependencies. You can install it using the installers below, or download a release binary from the releases page.
Jenkins integration for NodeJS & NPM packages
For example, the word token, which is mostly seen in lexing or parsing, was actually very common in the error messages he was receiving. It was the speed that first brought on the need for something new that led to the creation of Bun. At that time, Sumner was developing a game in Next.js but was frustrated with the speed of the iteration cycle. The James Webb Space Telescope Integrated Science Instrument Module reportedly embeds a standalone JavaScript engine that runs JS code. Chakra is the engine of the Internet Explorer browser. It was also forked by Microsoft for the original Edge browser, but Edge was later rebuilt as a Chromium-based browser and thus now uses V8. JavaScriptCore is Apple’s engine for its Safari browser.
Let’s start by writing an asynchronous Rust function that will create an instance of JsRuntime, which is responsible for JavaScript execution. Comptime is used in the lexical analyzer, called the “lexer,” one of the slowest parts of parsing for Bun.
Deno in Production
Next to the Deno runtime, Deno also provides a list of audited standard modules that are reviewed by the Deno maintainers and are guaranteed to work with a specific Deno version. Features like event listeners, timing functions and AJAX requests all sit in the Web APIs container until an action gets triggered.
These APIs are available on Windows 10 and any version of the Windows operating system that has Internet Explorer version 11.0 installed on the machine. Congratulations, our runjs runtime now works with the file system! Notice how little code was required to call from JavaScript to Rust – deno_core takes care of marshalling data between JavaScript and Rust so we didn’t need to do any of the conversions ourselves.
Meet Bun: A JavaScript Runtime for the Whole Dev Lifecycle
KJS from KDE was the starting point for its development. JavaScript engines are typically developed by web browser vendors, and every major browser has one.
When a function returns a value or gets sent to the Web APIs, it is popped off the stack. If a function doesn’t explicitly return a value then the engine will return undefined and also pop the function off the stack. This is what is meant by the term “JavaScript runs synchronously”; it is single-threaded, so can only do one thing at a time.
Notable engines
Except as otherwise noted, any code samples from the V8 project are licensed under V8’s BSD-style license. Other content on this page is licensed under the Creative Commons Attribution 3.0 License. Sumner is aware of this and credits the lack of widespread testing as one of the reasons why it’s so buggy. Of this he says, “bun doesn’t have enough test coverage and that’s why it’s so buggy.” Bun has a JavaScript test runner and the cli command is bun wiptest.
