Crossbrowser event trigger in pure JavaScript

trigger

var trigger = function (el, type) {
    var event;
    if (document.createEvent) {
        event=document.createEvent('HTMLEvents');
        event.initEvent(type,true,true);
    } else {
        event=document.createEventObject();
        event.eventType=type;
    }
    
    event.eventName=type;
    if (document.createEvent) {
        el.dispatchEvent(event);
    } else {
        el.fireEvent('on'+event.eventType,event);
    }
};