1、HTML
<!DOCTYPE html>
<html lang="en"> <head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>图片预加载</title>
</head> <body>
<div style="display: none">
<img data-src="data:images/arown.png" />
<img data-src="data:images/ewm2.png" />
<img data-src="data:images/hard.png" />
<img data-src="data:images/hard2.png" />
<img data-src="data:images/hard3.png" />
<img data-src="data:images/horizontal.jpg" />
<img data-src="data:images/loading-bj.png" />
<img data-src="data:images/loading-p1.gif" />
<img data-src="data:images/loading_bj.jpg" />
<img data-src="data:images/shoushi-text.png" />
<img data-src="data:images/shoushi.png" />
<img data-src="data:images/suotou.png" />
<img data-src="data:images/suotou2.png" />
<img data-src="data:images/suozi.png" />
<img data-src="data:images/touming.png" />
<img data-src="data:images/ts11.png" />
<img data-src="data:images/ts22.png" />
<img data-src="data:images/units-icons.png" />
<img data-src="data:images/video-img.jpg" />
<img data-src="data:images/1 (1).jpg" />
<img data-src="data:images/1 (10).jpg" />
<img data-src="data:images/1 (100).jpg" />
<img data-src="data:images/1 (101).jpg" />
<img data-src="data:images/1 (102).jpg" />
<img data-src="data:images/1 (103).jpg" />
<img data-src="data:images/1 (104).jpg" />
<img data-src="data:images/1 (105).jpg" />
<img data-src="data:images/1 (106).jpg" />
<img data-src="data:images/1 (107).jpg" />
<img data-src="data:images/1 (108).jpg" />
<img data-src="data:images/1 (109).jpg" />
<img data-src="data:images/1 (11).jpg" />
<img data-src="data:images/1 (110).jpg" />
<img data-src="data:images/1 (111).jpg" />
<img data-src="data:images/1 (112).jpg" />
<img data-src="data:images/1 (113).jpg" />
<img data-src="data:images/1 (114).jpg" />
<img data-src="data:images/1 (115).jpg" />
<img data-src="data:images/1 (116).jpg" />
<img data-src="data:images/1 (117).jpg" />
<img data-src="data:images/1 (118).jpg" />
<img data-src="data:images/1 (119).jpg" />
<img data-src="data:images/1 (12).jpg" />
<img data-src="data:images/1 (120).jpg" />
<img data-src="data:images/1 (121).jpg" />
<img data-src="data:images/1 (122).jpg" />
<img data-src="data:images/1 (123).jpg" />
<img data-src="data:images/1 (124).jpg" />
<img data-src="data:images/1 (125).jpg" />
<img data-src="data:images/1 (126).jpg" />
<img data-src="data:images/1 (127).jpg" />
<img data-src="data:images/1 (128).jpg" />
<img data-src="data:images/1 (129).jpg" />
<img data-src="data:images/1 (13).jpg" />
<img data-src="data:images/1 (130).jpg" />
<img data-src="data:images/1 (131).jpg" />
<img data-src="data:images/1 (132).jpg" />
<img data-src="data:images/1 (133).jpg" />
<img data-src="data:images/1 (134).jpg" />
<img data-src="data:images/1 (135).jpg" />
<img data-src="data:images/1 (136).jpg" />
<img data-src="data:images/1 (137).jpg" />
<img data-src="data:images/1 (138).jpg" />
<img data-src="data:images/1 (139).jpg" />
<img data-src="data:images/1 (14).jpg" />
<img data-src="data:images/1 (140).jpg" />
<img data-src="data:images/1 (141).jpg" />
<img data-src="data:images/1 (142).jpg" />
<img data-src="data:images/1 (143).jpg" />
<img data-src="data:images/1 (144).jpg" />
<img data-src="data:images/1 (145).jpg" />
<img data-src="data:images/1 (146).jpg" />
<img data-src="data:images/1 (147).jpg" />
<img data-src="data:images/1 (148).jpg" />
<img data-src="data:images/1 (15).jpg" />
<img data-src="data:images/1 (16).jpg" />
<img data-src="data:images/1 (17).jpg" />
<img data-src="data:images/1 (18).jpg" />
<img data-src="data:images/1 (19).jpg" />
<img data-src="data:images/1 (2).jpg" />
<img data-src="data:images/1 (20).jpg" />
<img data-src="data:images/1 (21).jpg" />
<img data-src="data:images/1 (22).jpg" />
<img data-src="data:images/1 (23).jpg" />
<img data-src="data:images/1 (24).jpg" />
<img data-src="data:images/1 (25).jpg" />
<img data-src="data:images/1 (26).jpg" />
<img data-src="data:images/1 (27).jpg" />
<img data-src="data:images/1 (28).jpg" />
<img data-src="data:images/1 (29).jpg" />
<img data-src="data:images/1 (3).jpg" />
<img data-src="data:images/1 (30).jpg" />
<img data-src="data:images/1 (31).jpg" />
<img data-src="data:images/1 (32).jpg" />
<img data-src="data:images/1 (33).jpg" />
<img data-src="data:images/1 (34).jpg" />
<img data-src="data:images/1 (35).jpg" />
<img data-src="data:images/1 (36).jpg" />
<img data-src="data:images/1 (37).jpg" />
<img data-src="data:images/1 (38).jpg" />
<img data-src="data:images/1 (39).jpg" />
<img data-src="data:images/1 (4).jpg" />
<img data-src="data:images/1 (40).jpg" />
<img data-src="data:images/1 (41).jpg" />
<img data-src="data:images/1 (42).jpg" />
<img data-src="data:images/1 (43).jpg" />
<img data-src="data:images/1 (44).jpg" />
<img data-src="data:images/1 (45).jpg" />
<img data-src="data:images/1 (46).jpg" />
<img data-src="data:images/1 (47).jpg" />
<img data-src="data:images/1 (48).jpg" />
<img data-src="data:images/1 (49).jpg" />
<img data-src="data:images/1 (5).jpg" />
<img data-src="data:images/1 (50).jpg" />
<img data-src="data:images/1 (51).jpg" />
<img data-src="data:images/1 (52).jpg" />
<img data-src="data:images/1 (53).jpg" />
<img data-src="data:images/1 (54).jpg" />
<img data-src="data:images/1 (55).jpg" />
<img data-src="data:images/1 (56).jpg" />
<img data-src="data:images/1 (57).jpg" />
<img data-src="data:images/1 (58).jpg" />
<img data-src="data:images/1 (59).jpg" />
<img data-src="data:images/1 (6).jpg" />
<img data-src="data:images/1 (60).jpg" />
<img data-src="data:images/1 (61).jpg" />
<img data-src="data:images/1 (62).jpg" />
<img data-src="data:images/1 (63).jpg" />
<img data-src="data:images/1 (64).jpg" />
<img data-src="data:images/1 (65).jpg" />
<img data-src="data:images/1 (66).jpg" />
<img data-src="data:images/1 (67).jpg" />
<img data-src="data:images/1 (68).jpg" />
<img data-src="data:images/1 (69).jpg" />
<img data-src="data:images/1 (7).jpg" />
<img data-src="data:images/1 (70).jpg" />
<img data-src="data:images/1 (71).jpg" />
<img data-src="data:images/1 (72).jpg" />
<img data-src="data:images/1 (73).jpg" />
<img data-src="data:images/1 (74).jpg" />
<img data-src="data:images/1 (75).jpg" />
<img data-src="data:images/1 (76).jpg" />
<img data-src="data:images/1 (77).jpg" />
<img data-src="data:images/1 (78).jpg" />
<img data-src="data:images/1 (79).jpg" />
<img data-src="data:images/1 (8).jpg" />
<img data-src="data:images/1 (80).jpg" />
<img data-src="data:images/1 (81).jpg" />
<img data-src="data:images/1 (82).jpg" />
<img data-src="data:images/1 (83).jpg" />
<img data-src="data:images/1 (84).jpg" />
<img data-src="data:images/1 (85).jpg" />
<img data-src="data:images/1 (86).jpg" />
<img data-src="data:images/1 (87).jpg" />
<img data-src="data:images/1 (88).jpg" />
<img data-src="data:images/1 (89).jpg" />
<img data-src="data:images/1 (9).jpg" />
<img data-src="data:images/1 (90).jpg" />
<img data-src="data:images/1 (91).jpg" />
<img data-src="data:images/1 (92).jpg" />
<img data-src="data:images/1 (93).jpg" />
<img data-src="data:images/1 (94).jpg" />
<img data-src="data:images/1 (95).jpg" />
<img data-src="data:images/1 (96).jpg" />
<img data-src="data:images/1 (97).jpg" />
<img data-src="data:images/1 (98).jpg" />
<img data-src="data:images/1 (99).jpg" /> </div> <div class="loadingpics">
<img id="loadingpics" src="data:images/loading-p1.gif" />
</div> <div class="loadingpics2">
<p class="perc_txt" style="color: #000">0%</p>
</div>
</body>
<script src="js/jquery-2.2.3.min.js"></script>
<script src="js/newpreLoad.js"></script>
<script>
var imgList = [];
$('img[data-src]').each(function () {
var src = $(this).data("src");
imgList.push(src);
})
var loadImg = new PreloadImg(imgList);
loadImg.loadImg();
</script> </html>
2、js
/**
* 自定义预加载图片的类
* param imgList传入的待加载图片数组
* param imgLoadAll待加载总数量
* param count已加载数量
*/
//判断是否微信登陆
var ua = window.navigator.userAgent.toLowerCase();
function isWeiXin() {
if (ua.match(/MicroMessenger/i) == 'micromessenger') {
return true;
} else {
return false;
}
} class PreloadImg {
constructor(imgList) {
this.imgList = imgList;
this.imgLoadAll = this.imgList.length;
this.count = 0;
this.per = 0;
}
// 遍历待加载的图片
loadImg() {
var that = this;
that.imgList.forEach(function (src, i) {
var newsrc = src.substring(src.length - 3);
if (newsrc === 'mp3') {
var audio = new Audio(src);
var loadType = false;
if (isWeiXin()) {
document.addEventListener("WeixinJSBridgeReady", function () {
audio.load();
audio.addEventListener('canplaythrough', function () {
if (!loadType) {
loadType = true;
that.callback();
}
}, false);
}, false);
} else {
audio.load();
audio.addEventListener('canplaythrough', function () {
if (!loadType) {
loadType = true;
console.log('歌曲下载完毕');
that.callback();
}
}, false);
}
} else {
var img = new Image();
img.onload = function () {
that.callback();
}
img.src = src;
}
});
}
// 加载完毕回调
callback() {
var that = this;
that.count = that.count + 1;
console.log(that.count)
that.per = Math.floor((that.count / that.imgLoadAll) * 100);
that.changePer(that.per);
if (that.per == 100) {
console.log('加载完毕');
}
}
// 更改DOM百分比样式
changePer(per) {
$(".perc_txt").html(per + "%");
}
}