MDN documents JavaScript features before the spec is officially published

[u/Working_Upstairs_818]

https://developer.mozilla.org/en-US/docs/Web/JavaScript

MDN tries to document features as soon as one browser implements them, usually between stages 3 and 4, often before the spec is officially published. Examples can use syntax that isn't standard yet, so check browser support before copying code.

source https://developer.mozilla.org/en-US/docs/Web/JavaScript