flexbox alerts with velocity

flexboxnotification.js

var modal = (function(base) {
  "use strict";

  var className = "itemContainer__item";
  var containerClassName = "itemContainer";
  var containerId = "bmk-itemContainer";
  var classSelector = "." + className;
  var container = elem({ 
    className: containerClassName,
    id: containerId
  }); 

  function init(opts) {
    var instance = new Factory(opts);   
    set(instance.modal);
  }

  function Factory(opts) {
    this.modal = elem(opts);
    document.getElementById(containerId).appendChild(this.modal);
  }

  function elem(opts) {
    var el = document.createElement("div");
    el.className = opts.className || className;
    if (opts.id) el.id = opts.id;
    if (opts.text) el.appendChild(document.createTextNode(shorten(opts.text)));
    return el;
  }

  function shorten(str) {
    return str.length > 50 ? str.substring(0, 50) + " ..." : str;
  }

  function set(el) {
    el.style.display = "initial";
    Velocity(el, {opacity: 0}, {delay: 2000, duration: 2000, complete: slice});
  }

  function slice(el) {
    el[0].parentNode.removeChild(el[0]);
  }
  
  base.appendChild(container);

  return init;

})(document.body);

modal({text: "slfjkajfjlfjaklfakjsfsjfsfsf"});