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What ‘use strict’ means for in JavaScript

chokri profile image Chokri K' Originally published at on ・1 min read

“strict mode”;

It’s a ECMAScript 5 feature that prevents certain actions from being taken and throws more exceptions in a JavaScript code.

The strict mode is necessary if you have a complex code to write. It introduces better error-checking, If you have a calculating algorithm.

Without this mode you can write console.log(Infinity = 0) and there is no problem with that. This will return 0 as inspected and Error “TypeError: “Infinity” is read-only”

We can use this feature into a function. For example:

// Non-strict code... (function(){ "use strict"; // Define your library strictly... })(); // Non-strict code...

But, if you activate it you’ll see a lot of problems on the console. To avoid that, try to write a clean code.

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