https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode#Securing_JavaScript
See the section '"Securing" JavaScript' of that page.
What does it mean by exposing the global object in browsers? Isn't the global object the window itself? Is it not always exposed?
Before that they mention this
"Some websites now provide ways for users to write JavaScript which will be run by the website on behalf of other users. JavaScript in browsers can access the user's private information, so such JavaScript must be partially transformed before it is run, to censor access to forbidden functionality".
Is it something specific to those cases?