event handling on data-attrs

data.events.js

(function (root) {

  /**
   * data events add event listeners
   * on data-attributes, ie8+
   *
   * author: dhigginbotham
   * license: MIT
   */

  var priv = {},
    events = {};

  /**
   * internal events on the dom
   */
  priv.events = [];

  /**
   * helper to get index of event
   */
  priv.contains = function (attr) {
    return priv.events.indexOf(attr);
  };
  
  /**
   * get elements querySelector
   */
  priv.select = function (attr) {
    return document.querySelector('[data-' + attr + ']');
  }

  /**
   * turns an event on
   */
  events.on = function (attr, ev, fn) {
    var el = priv.select(attr);
    if (priv.contains(attr) == -1) priv.events.push(attr);
    if (el.addEventListener) {
      return el.addEventListener(ev, fn, false);
    } else if (el.attachEvent) {
      return el.attachEvent('on' + ev, fn);
    };
  };

  /**
   * turns an event off
   */
  events.off = function (attr, ev, fn) {
    var el = priv.select(attr);
    if (priv.contains(attr) != -1) priv.events.splice(priv.contains(attr), 1);
    if (el.removeEventListener) {
      return el.removeEventListener(ev, fn, false);
    } else if (el.detachEvent) {
      return el.detachEvent('on' + ev, fn);
    };
  };

  /**
   * toggle an event on or off, so you don't have
   * to keep track of it.
   */
  events.toggle = function (attr, ev, fn) {
    if (priv.contains(attr) == -1) {
      events.on(attr, ev, fn);
    } else {
      events.off(attr, ev, fn);
    }
  };

  /**
   * expose public api
   */
  if (typeof SM != 'undefined') {
    SM.namespace('SM.dataEvents');
    _.extend(SM.dataEvents, events); // feels pointless
  } else {
    root.dataEvents = events;
  }
}(window));

example.js

var handler = function (e) {
  console.log(e);
};

dataEvents.toggle('someDataAttr', 'click', handler); // first time, turns it on, second time turns it off.