JQuery :: Track Input Field Text And Run Function On The Fly?

How can I track what is written to an input field on the fly(event that is not "click" "hover" etc but something like "track" or "observe")?Lets say I have a js object like this:

var array1 = {id1: 'keyword', id2: 'execute', id3: 'go'};

And 3 input fields like this:

<input id"id1" name="id1"></input>
<input id"id2" name="id2"></input>
<input id"id3" name="id3"></input>

I want to track the input fields so that

if(
the string "keyword" is written to the id1 field
the string "execute" is written to the id2 field

[code]....