Code snippet:

var role=s[0].Role;// role contains string value 
dijit.byId("editRole").attr("Value",getRoleByName(role));

function getRoleByName(role)
{
    var roleVal;
    alert(role);
    switch(role)
    {
        case 'Basic User' :roleVal='1';break;
        case 'Network Operator' :roleVal='3';break;
        case 'System Administrator' :roleVal='5';break;
        case 'Custom Level 1' :roleVal='11';break;
        case 'Custom Level 2' : roleVal='12';break;
        default: roleVal='1';break;
    }
    return roleVal;
}

When I tried to call the Javascript method which has the switch statement in it I am getting below error in IE8, but in Firefox is working fine..

Error in Developers tools:

method Error executing: function(/*Event*/ e){
    // summary:
    // Handler when the user activates the button portion.
    if(this._onClick(e) === false){ // returning nothing is same as true
        e.preventDefault(); // needed for checkbox
    } else if (this.type == "submit" && !this.focusNode.form){ // see if a nonform widget needs to be signalled
        for(var node=this.domNode; node.parentNode/*#5935*/; node=node.parentNode){
            var widget=dijit.byNode(node);
            if(widget && typeof widget._onSubmit == "function"){
                widget._onSubmit(e);
                break;
            }
        }
    }
}TypeError: Object doesn't support this property or method

Can anyone help me with this? ...how to overcome this problem?...

Error youre showing is not related to the below code. As the dojotoolkit-src commenting kindly shows you is, that it has to do with the function 'Handler when the user activates the button portion.'

Should fix this

 // << Value is all lower case
 dijit.byId("editRole").attr("Value",getRoleByName(role)); 

And a little cleaner coded switch with a 'WTF' - im thinking it might be the syntax highlighting youre experimenting with here - or are those tildes really in your code?

 // What are these back-tilds doing here?
 switch(role)``  
 {
      case 'Basic User'           : return 1
      case 'Network Operator'     : return 3
      case 'System Administrator' : return 5
      case 'Custom Level 1'       : return 11
      case 'Custom Level 2'       : return 12
      default:
           return 1
     // return works as your break does, it stops the switch
}

Saying your hitting problem during a trim? Try this, trim is not implemented in all javascript engines

if(typeof String.prototype.trim !== 'function') {
        String.prototype.trim = function() {
                return this.replace(/^\s+|\s+$/g, ''); 
        }
}