javascript-patterns/function-patterns/init-time-branching.html at master · cyberpython/javascript-patterns · GitHub

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<!doctype html>
<html lang="en">
<head>
<title>JavaScript Patterns</title>
<meta charset="utf-8">
</head>
<body>
<script>
/* Title: Init-time branching
   Description: branch code once during initlization initialization
*/

// BEFORE
/* var utils = {
  addListener: function (el, type, fn) {
    if (typeof window.addEventListener === 'function') {
      el.addEventListener(type, fn, false);
    } else if (typeof document.attachEvent === 'function') {
      el.attachEvent('on' + type, fn);
    } else {
      el['on' + type] = fn;
    }
  },
  removeListener: function (el, type, fn) {
  }
}; */

// the interface
var utils = {
  addListener: null,
  removeListener: null
};

// the implementation
if (typeof window.addEventListener === 'function') {
  utils.addListener = function (el, type, fn) {
    el.addEventListener(type, fn, false);
  };
} else if (typeof document.attachEvent === 'function') { // IE
  utils.addListener = function (el, type, fn) {
    el.attachEvent('on' + type, fn);
  };
  utils.removeListener = function (el, type, fn) {
    el.detachEvent('on' + type, fn);
  };
} else { // older browsers
  utils.addListner = function (el, type, fn) {
    el['on' + type] = fn;
  };
  utils.removeListener = function (el, type, fn) {
    el['on' + type] = null;
  };
}

// reference
// http://www.jspatterns.com/
// http://shop.oreilly.com/product/9780596806767.do?sortby=publicationDate
</script>
</body>
</html>