jq 图片懒加载

function lazyImg() {
      $("#de_content img").each(function () {
            $(this).addClass("lazy");
            $(this).css({ "width": "800px", "height": "400px" });
            var me = $(this);
            var sr = me.attr("src");
            me.attr("src", me.attr("data-src"));
            me.attr("data-src", sr);
      });
      var img = document.querySelectorAll("img[data-src]")
      for (var i = 0; i < img.length; i++) {
            img[i].style.opacity = "0"
      }
      Limg()
}
$(".content_right").ready(function () {
      setInterval(function () {
            $(this).scrollTop(function () {
                  Limg()
            })
      }, 1000)
})
function Limg() {
      var viewHeight = document.documentElement.clientHeight
      var limg = document.querySelectorAll("img[data-src]")
      Array.prototype.forEach.call(limg, function (item, index) {
            var rect
            if (item.getAttribute("data-src") === "")
                  return
            rect = item.getBoundingClientRect()
            if (rect.bottom >= 0 && rect.top < viewHeight) {
                  (function () {
                        var img = new Image()
                        img.src = item.getAttribute("data-src")
                        item.src = img.src
                        var j = 0
                        setInterval(function () {
                              j += 0.2
                              if (j <= 1) {
                                    item.style.opacity = j
                                    return
                              }
                        }, 100)
                        item.removeAttribute('data-src')
                  })()
            }
      })
}