No! Fable (http://fable.io) is an open source compiler that brings all the power of F# to the JS world: the functional paradigm, static typing with type inference, pattern matching, type providers and more. Together with a comprehensive library to handle collections, text and observables among others.
Fable doesn't add any runtime overhead and generates clean JS code in conformance with new ES6 patterns, like modules or iterables, making it compatible with modern development tools, including Github Electron or React Native to let you develop not only web, but also cross platform desktop and mobile apps.
In its short life Fable already has several projects in production like the amazing thegamma.net, and is very close to 1.0 release. In this talk you will learn about the coolest and newest features of Fable and the vast number of possibilities it opens for F# developers.