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.

Jul 8, 2025 · JavaScript's strict mode is a way to opt in to a restricted variant of JavaScript, thereby implicitly opting-out of "sloppy mode". Strict mode isn't just a subset: it intentionally has different …

Aug 26, 2009 · "use strict" makes JavaScript code to run in strict mode, which basically means everything needs to be defined before use. The main reason for using strict mode is to avoid …

Dec 3, 2024 · What is "use strict" in JavaScript? The "use strict" is the literal expression that enables strict mode for JavaScript. It is added at the top of a JavaScript file, function, or block, and tells the …

Feb 6, 2024 · In this article, you've learned about the strict mode, how to use it, and how it differs from writing JavaScript code in non-strict mode. You've also learned various contexts in JavaScript where …

In this tutorial, you will learn about the JavaScript 'use strict' syntax with the help of examples.

May 19, 2020 · Modern JavaScript supports “classes” and “modules” – advanced language structures (we’ll surely get to them), that enable use strict automatically. So we don’t need to add the "use …

May 20, 2025 · In this article, I’ll break down what "use strict" means in JavaScript, the problems it helps avoid, and when you should use it — with clear examples to guide you.

Sep 28, 2025 · Strict Mode is activated by adding 'use strict' at the beginning of a script or a function. Once enabled, JavaScript enforces stricter rules, making it simpler to identify errors early.

Nov 8, 2025 · 'use strict' is a directive (not a function, statement, or keyword) introduced in ECMAScript 5 (2009) that enables strict mode in JavaScript. When enabled, strict mode modifies the language’s …