“Strict mode” is used to refer to settings and pragmas which make some languages and systems more normal and less forgiving. Often such systems can be used for quick, one-off’ish, scripting needs in which case more leniency may be helpful but in cases where more substantial logic is being created it is desirable to configure the system to guard against misfiring black magic and DWIMmery.
"use strict"; as a statement enforces compliance with
newer ECMAScript standards.