Script for hiding Ribbon for Reader permission users

Link Referred  - http://sharepoint.smayes.com/2011/02/hiding-the-sharepoint-2010-ribbon-for-readers-a-proof-of-concept/

Insert the script after the below lines

div id="s4-ribbonrow" 
    
/div

Script

var ribbonRow = document.getElementById("s4-ribbonrow");

if ((ribbonRow.innerHTML.indexOf("Browse") == -1) && (ribbonRow.innerHTML.indexOf("Hide Ribbon") == -1) && (ribbonRow.innerHTML.indexOf("Show Ribbon") == -1))

{

            ribbonRow.style.display = "none";

}