“use strict” mode in JavaScript

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Strict Mode is a new feature in ECMASCRIPT 5 that makes your program or function in a 'strict' operating context. The strict context prevents certain functions from doing and throwing more exceptions with a trivially malformed way of logic.

Syntax to apply strict mode :

To use the strict mode in JavaScript use statement 'use strict';

Strict mode was a new feature in ECMAScript 5 that allows you to place a program or function in a 'strict' operating context. This strict reference prevents certain actions from happening and throwing more exceptions. statement 'use strict'; Instructs the browser to use strict mode, which is a less secure feature set of JavaScript.

Benefits of using strict: Strict mode introduces many changes to normal JavaScript semantics.

Strict mode eliminates some JavaScript silent errors by turning them into throw errors.
Strict mode make it easy to write the code in a 'safe' mode
Strict mode only disables functions that are not logically or syntactically.

Let's understand it with the help of an example :

<!DOCTYPE html>

<html>

<body>

<h2>Global 'use strict' declaration.</h2>

<p>Open a console window in your browser to view the error report (F12)</p>

<script>

    'use strict';

    myFunction();

    function myFunction() {

        x = 14;   // This will cause an error (y is not defined)

    }

</script>

</body>

</html>

When you run the above code you will find that in console it will throw an error 'strict.html:14 Uncaught ReferenceError: x is not defined'. This would be because of the strict method of Javascript.

Hope this description will be helpful for you.

Happy Coding!

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