codeforamerica/ohana-web-search

// Detects whether a particular event is supported.
// (from http://stackoverflow.com/questions/2877393/
// detecting-support-for-a-given-javascript-event)
function isEventSupported(eventName) {
  var TAGNAMES = {
    'select': 'input',
    'change': 'input',
    'submit': 'form',
    'reset': 'form',
    'error': 'img',
    'load': 'img',
    'abort': 'img'
  };
  var el = document.createElement(TAGNAMES[eventName] || 'div');
  eventName = 'on' + eventName;
  var isSupported = (eventName in el);
  if (!isSupported) {
    el.setAttribute(eventName, 'return;');
    isSupported = typeof el[eventName] === 'function';
  }
  el = null;
  return isSupported;
}

// @return [Object] The client window dimensions.
// (from http://stackoverflow.com/questions/3333329/
// javascript-get-browser-height)
function getWindowRect() {
  var myWidth = 0, myHeight = 0;
  if ( typeof( window.innerWidth ) === 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if ( document.documentElement &&
            ( document.documentElement.clientWidth ||
              document.documentElement.clientHeight )
            ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if ( document.body &&
            ( document.body.clientWidth || document.body.clientHeight )
            ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }

  return {
    'width':myWidth,
    'height':myHeight
  };
}

// Get left and top offset of an element
// (from http://stackoverflow.com/questions/8111094/
// cross-browser-javascript-function-to-find-actual-position-of-an-element-
// in-page)
// @return [Object] An object with top and left properties.
function getOffset(element) {
  var body = document.body,
  win = document.defaultView,
  docElem = document.documentElement,
  box = document.createElement('div');
  box.style.paddingLeft = box.style.width = '1px';
  body.appendChild(box);
  var isBoxModel = box.offsetWidth === 2;
  body.removeChild(box);
  box = element.getBoundingClientRect();
  var clientTop  = docElem.clientTop  || body.clientTop  || 0,
      clientLeft = docElem.clientLeft || body.clientLeft || 0,
      scrollTop  = (win && win.pageYOffset) ||
                    isBoxModel && docElem.scrollTop ||
                    body.scrollTop,
      scrollLeft = (win && win.pageXOffset) ||
                    isBoxModel && docElem.scrollLeft ||
                    body.scrollLeft;
  return {
    top : box.top  + scrollTop  - clientTop,
    left: box.left + scrollLeft - clientLeft
  };
}

// Get computed style
// (from http://stackoverflow.com/questions/2664045/
// how-to-retrieve-a-styles-value-in-javascript)
function getStyle(el, styleProp) {
  var value, defaultView = (el.ownerDocument || document).defaultView;
  // W3C standard way:
  if (defaultView && defaultView.getComputedStyle) {
    // Sanitize property name to CSS notation
    // (hyphen-separated words eg. font-size).
    styleProp = styleProp.replace(/([A-Z])/g, '-$1').toLowerCase();
    var style = defaultView.getComputedStyle(el, null);
    return style.getPropertyValue(styleProp);
  } else if (el.currentStyle) { // IE
    // sanitize property name to camelCase
    styleProp = styleProp.replace(/\-(\w)/g, function(str, letter) {
      return letter.toUpperCase();
    });
    value = el.currentStyle[styleProp];
    // convert other units to pixels on IE
    if (/^\d+(em|pt|%|ex)?$/i.test(value)) {
      return (function(value) {
        var oldLeft = el.style.left, oldRsLeft = el.runtimeStyle.left;
        el.runtimeStyle.left = el.currentStyle.left;
        el.style.left = value || 0;
        value = el.style.pixelLeft + 'px';
        el.style.left = oldLeft;
        el.runtimeStyle.left = oldRsLeft;
        return value;
      })(value);
    }
    return value;
  }
}

export default {
  isEventSupported:isEventSupported,
  getWindowRect:getWindowRect,
  getOffset:getOffset,
  getStyle:getStyle,
};