How to have a mouseover event fire only if the mouse is hovered over an element for at least 1 second?

hover_delay.js

var delay = function (elem, callback) {
    var timeout = null;
    elem.onmouseover = function() {
        // Set timeout to be a timer which will invoke callback after 1s
        timeout = setTimeout(callback, 1000);
    };

    elem.onmouseout = function() {
        // Clear any timers set to timeout
        clearTimeout(timeout);
    }
};


delay(document.getElementById('someelem'), function() {
    alert("Fired");
});