Case sensitive non verification in JS ?

Hello team,

During training JavaScript using PhpStrorm, I've take a lot of time trying to debugging a mistake of me.

On a line, I written :

var myButton = Document.querySelector('button');

instead of :

var myButton = document.querySelector('button');

those prevent triggering the script.

But PhpStorm analysis don't even returned a warning. Is it a normal behavior, like it is a  WebStorm's reserved feature or an oversight ?

Thanks in advance ! (Hope my non-native english is understanding btw...)