The purpose of “use strict” is to indicate that the code should be executed in “strict mode”. With strict mode, you can not, for example, use undeclared variables. All modern browsers support “use strict” except Internet Explorer 9 and lower: Directive.

Should I use strict mode?

Strict mode is an important part of modern JavaScript. It is a mode that lets us opt-in to a more restricted syntax of JavaScript. … Strict mode makes several changes to JavaScript semantics. It eliminates silent errors and instead throws them so that the code won’t run with errors in the code.

How do I get rid of use strict?

No, you can’t disable strict mode per function. Notice how we can define function outside of strict code and then pass it into the function that’s strict. You can do something similar in your example — have an object with “sloppy” functions, then pass that object to that strict immediately invoked function.