前端开发者| 前端开发需要会哪些技能 |
| 前端开发需要的代码编辑器 |
| 前端开发需要打字速度吗 |
html 代码片段
<!DOCTYPE html>
<html>
<head>
<meta charset=”utf-8″ />
<meta
name=”viewport”
content=”width=device-width, initial-scale=1.0, user-scalable=0, minimum-scale=1.0, maximum-scale=1.0″
/>
<title>lazyLoad</title>
<style type=”text/css” media=”all”>
body,
ul,
li {
padding: 0;
margin: 0;
}
body {
font-size: 12px;
-webkit-user-select: none;
-webkit-text-size-adjust: none;
font-family: helvetica;
}
.lazyLoad ul li {
height: 200px;
border: 1px solid red;
margin-bottom: 2px;
overflow: hidden;
text-align: center;
}
</style>
</head>
<body>
<div class=”lazyLoad”>
<ul>
<li>
<span data-src=”http://www.update8.com”>我不是图片啦</span>
</li>
<li>
<img
data-src=”http://www.update8.com/images/01.jpg”
alt=””
/>
</li>
<li>
<img
data-src=”http://www.update8.com/images/02.jpg”
alt=””
/>
</li>
<li>
<img
data-src=”http://www.update8.com/images/03.jpg”
alt=””
/>
</li>
<li>
<img
data-src=”http://www.update8.com/images/04.jpg”
alt=””
/>
</li>
<li>
<img
data-src=”http://www.update8.com/images/05.jpg”
alt=””
/>
</li>
<li>
<img
data-src=”http://cdn.guopan.cn/uploads/static/img/home-bg_3502fe8.jpg”
alt=””
/>
</li>
<li>
<img
data-src=”http://cdn.guopan.cn/uploads/ggimg/2016-01-11/20160111114705382.jpg”
alt=””
/>
</li>
<li>
<img
load-src=”http://cdn.guopan.cn/uploads/ggimg/2016-01-11/20160111113611440.jpg”
alt=””
/>
</li>
</ul>
</div>
<script>
var loadPic = function(obj, option) {
if (!obj) return
return new lazyLoad(obj, option)
}
function lazyLoad() {
this.init.apply(this, arguments)
}
lazyLoad.prototype = {
init: function(el, param) {
var opt = {
dataSrc: ‘lazyImg’,
dataImg:
‘http://misc.360buyimg.com/product/home/1.0.0/widget/floor/i/loading.gif’,
contens:
typeof el === ‘string’
? this.getElement(el)
: el || document.body,
cb: null,
}
if (param && param instanceof Object) {
for (var key in param) {
if (param.hasOwnProperty(key)) {
opt[key] = param[key]
}
}
}
console.log(opt)
this.opt = opt
this.render()
this.bindUI()
},
render: function() {
var _opt = this.opt,
_imgArr = [],
_dom = _opt.contens,
_img = _dom.querySelectorAll(‘[‘ + _opt.dataSrc + ‘]’)
if (_img.length) {
var _tagName
Array.prototype.forEach.call(
_img,
function(item, i) {
_tagName = item.tagName.toLowerCase()
if (
_tagName === ‘img’ &&
!item.getAttribute(‘src’)
) {
item.setAttribute(‘src’, this.opt.dataImg)
}
_imgArr.push({
obj: item,
tagName: item.tagName.toLowerCase(),
src: item.getAttribute(_opt.dataSrc),
})
}.bind(this),
)
}
this.imgArr = _imgArr
this.loadImg()
},
bindUI: function() {
window.addEventListener(
‘scroll’,
function(e) {
this.loadImg()
}.bind(this),
false,
)
},
loadImg: function() {
// console.log(this.imgArr);
var _imgArr = this.imgArr
var _dataSrc, _src
if (_imgArr.length) {
_imgArr.forEach(
function(item, i) {
if (this.isLoad(item.obj)) {
//如果是图片
if (item.tagName == ‘img’) {
_dataSrc = this.opt.dataSrc
_src = item.obj.getAttribute(_dataSrc)
if (_src) {
item.obj.setAttribute(‘src’, _src)
item.obj.removeAttribute(_dataSrc)
if (
typeof this.opt.cb ===
‘function’
) {
return this.opt.cb.call(
this,
item.obj,
)
}
}
} else {
//加载文件
if (typeof this.opt.cb === ‘function’) {
if (_imgArr[i].isLoad) {
return false
}
_imgArr[i].isLoad = 1
return this.opt.cb.call(
this,
item.obj,
)
}
}
}
}.bind(this),
)
}
},
isLoad: function(img) {
var _scrollTop =
document.body.scrollTop ||
document.documentElement.scrollTop
var _winHeight = window.innerHeight
var _offsetTop = img.offsetTop
var _height = img.offsetHeight
if (
_offsetTop + _height >= _scrollTop &&
_offsetTop <= _winHeight + _scrollTop
) {
return true
}
return false
},
getElement: function(o) {
return document.querySelector(o)
},
}
var t = loadPic(‘.lazyLoad’, {
dataSrc: ‘data-src’,
cb: function(item) {
console.log(item)
},
})
</script>
</body>
</html>
| 前端开发有哪些方向 |
| web前端开发常遇到的问题有哪些 |
| 前端开发文档有哪些 |
» 本文来自：前端开发者 » 《js懒加载图片特效》
» 本文链接地址：https://www.rokub.com/6451.html
» 您也可以订阅本站：https://www.rokub.com
评论前必须登录！
注册