Set the value of an input field
if your form contains an input field like
<input type='text' id='id1' />
then you can write the code in javascript as given below to set its value as
document.getElementById('id1').value='text to be displayed' ;
I use 'setAttribute' function:
<input type="text" id="example"> // Setup text field
<script type="text/javascript">
document.getElementById("example").setAttribute('value','My default value');
</script>
This is one way of doing it:
document.getElementById("nameofid").value = "My value";