The oninput property of the GlobalEventHandlers mixin is an event handler that processes input events on the <input>, <select>, and <textarea> elements. It also handles these events on elements where contenteditable or designMode are turned on.
Note: Unlike oninput, the onchange event handler is not necessarily called for each alteration to an element's value.
target.oninput = functionRef;
functionRef is a function name or a function expression. The function receives an InputEvent object as its sole argument.
This example logs the number of characters in an <input> element, every time you modify its contents.
<input type="text" placeholder="Type something here to see its length." size="50">
<p id="log"></p>
let input = document.querySelector('input');
let log = document.getElementById('log');
input.oninput = handleInput;
function handleInput(e) {
log.textContent = `The field's value is
${e.target.value.length} character(s) long.`;
}
The following links discuss compatibility issues and fixes that may be helpful when working with older browsers: