[runarberg]

I think this is the point of the stage 3 proposal.

Browser makers start implementing the feature and releasing it in the development and beta versions of their browsers. Then if the users of the experimental features start noticing that webpage break, the proposal will get an update.

If I remember correctly, this exact thing happened to `Array.prototype.flatten` which got renamed to `Array.prototype.flat` after it was realized that the former broke a lot of legacy webpages (and after a long discussion of `Array.prototype.smoosh`[1])

1: https://developers.google.com/web/updates/2018/03/smooshgate

[IainIreland]

In fact, it already happened to this proposal, which started life as `Array.prototype.item` before it turned out that some libraries were using the presence of a `.item` property to duck-type DOM collections:

https://github.com/tc39/proposal-relative-indexing-method#we...