How to define an input id in javascript? Help

Hi i am not to good in javascript. This is a part of code from my ajax search auto-suggest and i need to replace "the word" with the input id somehow and i dont know how to do it. need some help please.
here is a link to the entire code demo. http://jsfiddle.net/coladeu/Qhj5N/

<input type="text" id="[B]selectedInput[/B]"/><ul id="list"></ul>    
<script>    
[B]var keyword = "the word[/B][B]"; [/B] (wrong code)      
url: "http://itunes.apple.com/search?term="[B] + keyword +[/B] "&entity=musicTrack",
..

Code (markup):

 

look there is a text box with id="selectedInput" now what u have to do is make a variable like this in java script and stored that id which is in text box.
var x=document.getElementbyId("selectedInput").value;
using this variable you can store the text box value in var x and then u can use it where u need this variable.