JavaScript used to calculate new value as event responses
Value is shown to user, but not submitted to server
Inline element
<form>
<p>
<label>Name:
<input name="a" value="" />
</label>
</p>
<p>
<output name="greetings"
onforminput='value = "Hello" + a.value'>
Hello
</output>
</p>
</form>