You can achieve this with: EventTarget.dispatchEvent(event) and by passing in a new KeyboardEvent as the event.
For example: element.dispatchEvent(new KeyboardEvent('keypress', {'key': 'a'}))
Working example:
// get the element in question const input = document.getElementsByTagName("input")[0]; // focus on the input element input.focus(); // add event listeners to the input element input.addEventListener('keypress', (event) => { console.log("You have pressed key: ", event.key); }); input.addEventListener('keydown', (event) => { console.log(`key: ${event.key} has been pressed down`); }); input.addEventListener('keyup', (event) => { console.log(`key: ${event.key} has been released`); }); // dispatch keyboard events input.dispatchEvent(new KeyboardEvent('keypress', {'key':'h'})); input.dispatchEvent(new KeyboardEvent('keydown', {'key':'e'})); input.dispatchEvent(new KeyboardEvent('keyup', {'key':'y'}));<input type="text" placeholder="foo" />