https://ourtourismnews.com/wp-content/themes/News/assets/js/lazy.js

1/* lazyload.js (c) Lorenzo Giuliani
2 * MIT License (http://www.opensource.org/licenses/mit-license.html)
3 *
4 * expects a list of:  
5 * `<img src="blank.gif" data-src="my_image.png" width="600" height="400" class="lazy">`
6 */
7
8!function(window){
9  var $q = function(q, res){
10        if (document.querySelectorAll) {
11          res = document.querySelectorAll(q);
12        } else {
13          var d=document
14            , a=d.styleSheets[0] || d.createStyleSheet();
15          a.addRule(q,'f:b');
16          for(var l=d.all,b=0,c=[],f=l.length;b<f;b++)
17            l[b].currentStyle.f && c.push(l[b]);
18
19          a.removeRule(0);
20          res = c;
21        }
22        return res;
23      }
24    , addEventListener = function(evt, fn){
25        window.addEventListener
26          ? this.addEventListener(evt, fn, false)
27          : (window.attachEvent)
28            ? this.attachEvent('on' + evt, fn)
29            : this['on' + evt] = fn;
30      }
31    , _has = function(obj, key) {
32        return Object.prototype.hasOwnProperty.call(obj, key);
33      }
34    ;
35
36  function loadImage (el, fn) {
37    var img = new Image()
38      , src = el.getAttribute('data-src');
39    img.onload = function() {
40      if (!! el.parent)
41        el.parent.replaceChild(img, el)
42      else
43        el.src = src;
44
45      fn? fn() : null;
46    }
47    img.src = src;
48  }
49
50  function elementInViewport(el) {
51    var rect = el.getBoundingClientRect()
52
53    return (
54       rect.top    >= 0
55    && rect.left   >= 0
56    && rect.top <= (window.innerHeight || document.documentElement.clientHeight)
57    )
58  }
59
60    var images = new Array()
61      , query = $q('img.lazy')
62      , processScroll = function(){
63          for (var i = 0; i < images.length; i++) {
64            if (elementInViewport(images[i])) {
65              loadImage(images[i], function () {
66                images.splice(i, i);
67              });
68            }
69          };
70        }
71      ;
72    // Array.prototype.slice.call is not callable under our lovely IE8 
73    for (var i = 0; i < query.length; i++) {
74      images.push(query[i]);
75    };
76
77    processScroll();
78    addEventListener('scroll',processScroll);
79
80}(this);