what’s the equivalent of jquery’s ‘trigger’ method without jquery?

event.initMouseEvent(“click”…

Here is an example:

function simulateClick(elId) {
    var evt;
    var el = document.getElementById(elId);
    if (document.createEvent) {
        evt = document.createEvent("MouseEvents");
        evt.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
    }
    (evt) ? el.dispatchEvent(evt) : (el.click && el.click());
}

var foo = document.getElementById("hey");

foo.onclick = function () {alert("bar");}

simulateClick("hey");