The onchange
property of the GlobalEventHandlers
mixin is an event handler for processing change
events.
change
events fire when the user commits a value change to a form control. This may be done, for example, by clicking outside of the control or by using the Tab key to switch to a different control.
Note: Unlike oninput
, the onchange
event handler is not necessarily called for each alteration to an element's value
.
target.onchange = functionRef;
functionRef
is a function name or a function expression. The function receives an Event
object as its sole argument.
This example logs the number of characters in an <input>
element, every time you modify its contents and then change focus away from it.
<input type="text" placeholder="Type something here, then click outside of the field." size="50">
<p id="log"></p>
let input = document.querySelector('input');
let log = document.getElementById('log');
input.onchange = handleChange;
function handleChange(e) {
log.textContent = `The field's value is
${e.target.value.length} character(s) long.`;
}