Append value to an input field in Javascript

Question

Here i'm trying to append some text to an input field but everytime the old value gets replaced with new value.

HTML

<input type="text" id="taginput" class="input" name="tags">

Javascript

function update(i){
 document.getElementById('taginput').value = i.innerHTML;
  }

no jquery please.

Solution

You have to get the old value first, and then add to it

function update(i){
    var elem = document.getElementById('taginput');
    var old  = elem.value;
    elem.value = old + i.innerHTML;
}

or you could add it to with += directly

elem.value += i.innerHTML;