# use-strict

#### What does `'use strict'` do and what are some of the key benefits to using it? <a href="#what-does-use-strict-do-and-what-are-some-of-the-key-benefits-to-using-it" id="what-does-use-strict-do-and-what-are-some-of-the-key-benefits-to-using-it"></a>

**Answer**

Including `'use strict'` at the beginning of your JavaScript source file enables strict mode, which enforces more strict parsing and error handling of JavaScript code. It is considered a good practice and offers a lot of benefits, such as:

* Easier debugging due to eliminating silent errors.
* Disallows variable redefinition.
* Prevents accidental global variables.
* Oftentimes provides increased performance over identical code that is not running in strict mode.
* Simplifies `eval()` and `arguments`.
* Helps make JavaScript more secure.

**Good to hear**

* Eliminates `this` coercion, throwing an error when `this` references a value of `null` or `undefined`.
* Throws an error on invalid usage of `delete`.
* Prohibits some syntax likely to be defined in future versions of ECMAScript

**Additional links**

* [MDN docs for strict mode](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode)


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