I solved it using above code as mentioned by McDonald. Thanks

 Thanks for your reply. Here is what I am trying to do. I have a search button which when clicked pop up a modal pop up where the users search for some criteria once they click the get button on the modal pop up I am creating a new row on the webgrid which is on my page. What I want is when they again click on the same search which has the same criteria it should not create a new row. Basially no row should be same in my webgrid. I hope i made it clear. here is what I am using right now:

function PopulateIndividualGrid( Id,type,name))
    {
        debugger;   
         var grid = igtbl_getGridById('<%=grid.ClientID %>');       
         var gridRow;     

         var activeRow = igtbl_getActiveRow('<%=grid.ClientID %>');
         if(activeRow!=null)         
         {
            gridRow = igtbl_addNew('<%=grid.ClientID %>',0);
               
         }
         else
         {           
            igtbl_setActiveRow('<%=grid.ClientID %>',igtbl_getElementById('<%=grid.ClientID %>'));
            gridRow = igtbl_addNew('<%=grid.ClientID %>',0);
         }
                  
         gridRow.getCell(0).setValue(id);
         gridRow.getCell(1).setValue(type);
         gridRow.getCell(2).setValue(name);           ;                  

    }

So I have the ID which I am passing to this function. Now before adding a new row I want to iterate through my grid and see if this id already exists in some row. Please suggest.  Thanks