[JavaScript] What Is "use strict"?

Question

I've seen people using the line "use strict" in their JavaScript code and I'd like to know what it is. Any thorough explanation will be appriciated☺☺

Answer 1

The "use strict" makes JavaScript engine adheres to modern implementations. Example let, const, class etc

Answer 2

Thanks to any further answer, found an article on it through an SO thread, I'm bookmarking it myself: https://johnresig.com/blog/ecmascript-5-strict-mode-json-and-more/