I was trying to figure out how to auto-populate the input value base on what was entered in another input field using javascript. Here's my code:

<script>

add = document.getElementById('address').value;

city = document.getElementById('city').value;

state = document.getElementById('state').value;

zip = document.getElementById('zip').value;

compAdd = add+ +city+ +state+ +zip;

function showAdd(){

    document.getElementById('shipadd1').value=compAdd;

    document.getElementById('add1').innerHTML=compAdd;

}

</script>



<form action= onchange=showAdd();>



Home Address: <input id=address name=address type=text  /><br/>

Apt or Suite Number: <input id=suite name=suite type=text /><br/>

City/Town: <input id=city name=city type=text /><br/>

State:<select id=state name=state value=>...</select><br/>

Zip:<input id=zip name=zip type=text value=/><br/>





<p> Select Shipping Address Below: </p>



<input type=checkbox id=shipping-address-1 name=address1 value=><span id=shiadd1>(Print auto-populated shipping address here...)</span>



<input type=checkbox id=shipping-address-2 name=address2 value=>ABC Corp 123 Main Street, My City, State Zip

</form>