Retreive Text

Probobly really easy for most of you but...

How would I retreive whatever was typed into a text box. I have a button and a place for the user to enter text. When the button was pressed I call a function and i want it to compare the users text with other values.

I thought this would do it? (Abbreviation is the name of the textbox).

function def()
{

if (document.all.Abbreviation.value == 'A') {
document.all.Abbreviation.value='It worked';

}

this is javascript.

My Bad..

Moved from ClassicVB.