[fineline]

JS in the browser has direct integration to the DOM, networking, various local data persistence APIs, and other IO and sensors (webcam, accelerometer...) etc. Rust can be compiled to run in a sandbox, which can then be integrated via a remote call interface with the JS layer, and thus be indirectly (via JS) connected to the above APIs, but there are currently concerns around the performance of this approach. Rust cannot independently manage a web page which hosts it, without JS. There is some way to go before browsers support practical, accessible and performant front-end web apps in Rust.