用JS选择时的回声选项值

Question

I am trying to print a value in a printchatbox with javascript. When you select a specific option from a 'select', I need that value to be printed. Right now what I made is this:

<div class='printchatbox' id='printchatbox'></div>
<select type='text' id='km' name='km' value=''>
  <option value='1'>Number 1</option>
  <option value='2'>Number 2</option>
 </select>

<script>
// elements
var inpKm = document.getElementById("km");
var chBox = document.getElementById('printchatbox');
// event at keyup
inpKm.addEventListener('keyup', verbruik);
// function with event
function verbruik() {
    var km = Number(inpKm.value.replace(',','.'));
    // check for '', null, undefined, false, 0, NaN
    if (!km) {
        chBox.innerHTML = 'Select option.';
    } else {
        chBox.innerHTML = km;
    }
}
</script>

But it doesn't work unfortunately, and I don't know why. The selection is not echoed into the chatbox. How can I fix it? Thanks in advance!

Here's a link to the code https://jsfiddle.net/3hLm0t9L/11/

Answer 1

It's because you bound a keyup event instead of the change event.

This line:

inpKm.addEventListener('keyup', verbruik);

Should be:

inpKm.addEventListener('change', verbruik);

Also, even if you're dutch, it's good practice to code in english. This to say, you should keep your variables etc. in english. It's just good practice and allows any programmer to interact with it.