Strict Mode (JavaScript)

Strict mode is an opt-in mode that makes JavaScript catch more mistakes by turning silent errors into thrown errors. You enable it with the line "use strict".

Welcome to LearnCodingFast — free, interactive programming lessons covering Python, JavaScript, Java, C++, C#, SQL, HTML/CSS, React, AI and more. Every course is hands-on with examples you can run in your browser.

Loading interactive version…