<form>
<script type="text/javascript">
function doAction(value)
{
// Don't really have anything to set...just show the value
alert(value);
}
</script>
<input type="button" value="Add" onclick="doAction(this.value)">
<input type="button" value="Edit" onclick="doAction(this.value)">
<input type="button" value="Remove" onclick="doAction(this.value)">
</form>
There are other ways that involve not even passing the button's value, but they're not as compatible across browsers (IE uses a slightly different event model).
Of course, if you can get by without doing it in Javascript, and can just pass the clicked button to the server, it gets even easier than that...
<form>
<input type="submit" name="action" value="Add">
<input type="submit" name="action" value="Edit">
<input type="submit" name="action" value="Remove">
</form>
and whichever button you click gets put into the url as action=Add or whatever.