$(document).ready() fires too early

Question

So, I need to know the width of an element with javascript, the problem I have is that the function fires too early and the width changes when the css is tottally applied. A

Answer 1

Quote OP:

"As I understood, the $(document).ready() function was fired when the document is completed,"

$(document).ready() fires when the DOM ("document object model") is fully loaded and ready to be manipulated. The DOM is not the same as the "document".

W3C - DOM Frequently Asked Questions

You can try $(window).load() function instead...

$(window).load(function() {
    // your code
});

It will wait for all the page's assets (like images and fonts, etc.) to fully load before firing.