js change event code example

Example 1: js select on change value

document.getElementById('my-select').addEventListener('change', function() {
  console.log('You selected: ', this.value);
});

Example 2: javascript input value change

function updateInput(ish){
    document.getElementById("fieldname").value = ish;
}

Example 3: on change event html not working

onchange is only triggered when the control is blurred. Try onkeypress instead.