JavaScript'sstrict mode is a way toopt in to a restricted variant of JavaScript, thereby implicitly opting-out of "sloppy mode". Strict mode isn't just a subset: itintentionally has different semantics from normal code.

Strict mode for an entire script is invoked by including the statement"use strict"; before any other statements.

See also

• Strict mode
• Related glossary terms:
  • Sloppy mode