Simple login form with vanilla HTML markup
It's in the HTML (script tag). Link it. Keep 'em separated whenever possible.
Not a big deal but when declaring vars you can do them with one var statement, e.g. var a = 0, b = 3;
Add 'use strict;' to look super cool (but I've seen at least one thing that will break)
Fix stuff like linkLocation = 'home.html'; (no var statement - would be global - illegal in strict mode)
window is global in browsers. window.location can just be called as location
If this is to be seen by interviewers, be consistent with your style. For instance, you  mix ' and " for strings. Most prefer ' to differentiate from HTML attribute quotes which are typically double. Mixing both looks like it's not all your code or you're a little sloppy.
When it's just a JavaScript object and not JSON, it doesn't need quotes on the property names. e.g. send = { 'password':...
If it's an interview situation, don't pretend any of the regEx is yours unless you can explain it.
You're pooping all over the global namespace - quick fix would be:

(function(){

//wrap your code here

})()


Don't know what's wrong with code formatting but that puts your functions in scope with anonymous function that automatically fires so it should keep your stuff from being overwritten or overwriting other stuff in the global namespace.

Otherwise it looks like good, clean, straightforward, procedural code. Nothing wrong with that when it's all that's called for. If this were a heavy, complicated, application, I'd be wondering where the objects were at.