Question: I'm sure there is a simple error I'm making, but I am simply alerting `$(window).height()` and it returns the same value as `$(document).height()`.

I am on a 13" MBA and my window height of my browsers when maximised between 780px - 820px (roughly) but each time it returns a window height identical to that of document height. In every case on the site I am working on it is over 1000px.

What is going on here?

```
alert($(window).height());
alert($(document).height()); 

```

Answer: 
With no `doctype` tag, Chrome reports the same value for both calls.

Adding a strict doctype like `<!DOCTYPE html>` causes the values to work as advertised.

The `doctype` tag must be the *very* first thing in your document. E.g., you can't have any text before it, even if it doesn't render anything.
Here's a question and answer for this: [Difference between screen.availHeight and window.height()](https://stackoverflow.com/questions/3044230/difference-between-screen-availheight-and-window-height)

Has pics too, so you can actually see the differences. Hope this helps.

Basically, `$(window).height()` give you the maximum height inside of the browser window (viewport), and`$(document).height()` gives you the height of the document inside of the browser. Most of the time, they will be exactly the same, even with scrollbars.