Run javascript function when user finishes typing instead of on key up?

The solution below solves this problem and will call X seconds after finished as the OP requested. It also no longer requires the redundant keydown function. I have also added a check so that your function call won’t happen if your input is empty.

With JQuery

//setup before functions
var typingTimer; //timer identifier
var doneTypingInterval = 5000; //time in ms (5 seconds)

//on keyup, start the countdown
$('#myInput').keyup(function() {
    clearTimeout(typingTimer);
    if ($('#myInput').val()) {
        typingTimer = setTimeout(doneTyping, doneTypingInterval);
    }
});

//user is "finished typing," do something
function doneTyping() {
    //do something
    alert('Hello')
}

Example:

With Vanilla JavaScript solution:

//setup before functions
let typingTimer; //timer identifier
let doneTypingInterval = 5000; //time in ms (5 seconds)
let myInput = document.getElementById('myInput');

//on keyup, start the countdown
myInput.addEventListener('keyup', () => {
    clearTimeout(typingTimer);
    if (myInput.value) {
        typingTimer = setTimeout(doneTyping, doneTypingInterval);
    }
});

//user is "finished typing," do something
function doneTyping() {
    //do something
    alert('With Vanila Js');
}

Example: