Atwood's Law
Any application that can be written in JavaScript, will eventually be written in JavaScript.
Ultimately this law concerns software distribution: the web is the best mechanism for distributing software, JavaScript is the language of the web, hence Atwood’s law. It might be updated some day to include WASM, though that’s yet to be seen. Certainly the years since this blog post was published seem to have vindicated the law, though the growth of embedded systems in everything from cars to toasters runs counter to Atwood’s original point.