set cursor to end point when focus or change value of input text field

gistfile1.js

function SetEnd(txt) {  
      if (txt.createTextRange) {  
       //IE  
       var FieldRange = txt.createTextRange();  
       FieldRange.moveStart('character', txt.value.length);  
       FieldRange.collapse();  
       FieldRange.select();  
       }  
      else {  
       //Firefox and Opera  
       txt.focus();  
       var length = txt.value.length;  
       txt.setSelectionRange(length, length);  
      }  
}