"use strict" in javascript [duplicate]

Question

This question already has answers here:

What does "use strict" do in JavaScript, and what is the reasoning behind it? (29 answers)

Closed 9 years ago.

I have been reading many JavaScript codes recently and I was wondering of what are the benefits of using "use strict". Any idea would be very much appreciated.

Answer 1

Before you go and put "use strict" on all your scripts, a warning:

Browsers that do not support strict mode, will run your code with different behavior from browsers that do.

Now, to answer your question. The benefits of strict mode are:

1. Some errors are no longer silent and throw instead.
2. Allows the interpreter to make optmizations.
3. Prohibits syntax that will likely be deprecated in the next version of ECMAScript.

(Source: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Functions_and_function_scope/Strict_mode)

Answer 2

It activates strict mode (where supported). The main benefits are that some silent errors and some coding practices that can trip you up are turned into loud errors so you can avoid them entirely.