If you’re starting to encode javascript or you are already a javascript programmer and have never seen the strict mode before, check out this post.

About strict mode

I always recommend coding javascript in strict mode. Strict mode makes changes to normal javascript semantics. An important aspect is that the strict mode eliminates silent errors, forcing you to write a better code and don’t make mistakes.

Invoking strict mode

To invoke the strict mode, you just need to write ‘use strict’; in your javascript file, for example.

'use strict';

Now that you already know how to invoke strict mode, let’s see a quick example.

Quick example

'use strict';
foo = 'Guilherme'; // ReferenceError

The error occurs because you need to declare the variable.

'use strict';
var foo = 'Guilherme'; // It works!

Now it works!

Conclusion

As you can see, strict mode can help you a lot to write a better javascript code. If you wanna see more examples and know more how it exactly works, take a look: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode