Document
//REM
~function(){
document.documentElement.style.fontSize = document.documentElement.clientWidth/640*100 + 'px';
}()
//页面中如果自己使用了TOUCH MOVE等原生事件，需要把浏览器的默认行为阻止掉
$(document).on('touchmove touchstart touchend',function(ev){
ev.preventDefault();
})
//BANNER
var bannerRender = (function(){
var winW = document.documentElement.clientWidth,
maxL = 0,
minL = 0;
var $banner = $('.banner'),
$wrapper = $banner.children('.wrapper'),
$slideList = $wrapper.children('.slide'),
$imgList = $wrapper.find('img');
var step = 1,
count = 0,
followTimer = null;
//public fn
function isSwipe(strX,strY,endX,endY){
return Math.abs(endX - strX)>30 || Math.abs(endY - strY) > 30)
}
function swipeDir(strX,strY,endX,endY){
return Math.abs(endX - strX)>=Math.abs(endY - strY)?(endX - strX>0?'right':'left'):(endY - strY>0?'down':'up');
}
//touch start
function dragStart(ev){
var point = ev.touches[0];
$wrapper.attr({
strL:parseFloat($wrapper.css('left')),
strX:point.clientX,
strY:point.clientY,
isMove:false,
dir:null,
changeX:null
})
}
//touch move
function dragIng(ev){
var point = ev.touches[0];
var endX = point.clientX,
endY = point.clientY,
strX = parseFloat($wrapper.attr('strX')),
strY = parseFloat($wrapper.attr('strY')),
strL = parseFloat($wrapper.attr('strL')),
changeX = endX - strX;
//计算出是否滑动以及滑动的方向：只有是左右滑动才进行处理
var isMove = isSwipe(strX,strY,endX,endY),
dir = swipeDir(strX,strY,endX,endY);
if(isMove && /(left|right)/i.test(dir)){
$wrapper.attr({
isMove:true,
dir:dir,
changeX:changeX
});
var curL = strL+changeX;
curL = curL>maxL?maxL:(curL=winW/2){
if(dir==='left'){
step++;
}else{
step--;
}
}
}
$wrapper[0].style.webkitTransitionDuration = '.2s';
$wrapper.css('left',-step*winW);
lazyImg();
//动画运动过程中，我们监听一个定时器:动画运动完成判断当前是否运动到边界，如果运动到达了边界，我们让其立马回到自己的真实位置
window.clearTimeout(followTimer)
followTimer = window.setTimeout(function(){
if(step===0){
$wrapper[0].style.webkitTransitionDuration = '0s';
$wrapper.css('left',-(count-2)*winW);
step = count-2;
lazyImg();
}
if(step===count-1){
$wrapper[0].style.webkitTransitionDuration = '0s';
$wrapper.css('left',-winW);
step = 1;
lazyImg();
}
window.clearTimeout(followTimer)
},200)
}
//图片延迟加载，让当前的活动块及相邻的两个活动块进行加载
function lazyImg(){
var $cur = $slideList.eq(step),
$tar = $cur.add($cur.prev()).add($cur.next());
$tar.each(function(index,item){
var $img = $(item).children('img');
if($img.attr('isLoad')==='true'){
//ATTR存储或者获取的属性值都是一个字符串，如果当前的图片已经加载过了，我们就不需要重新的加载了
return;
}
var oImg = new Image;
oImg.src = $img.attr('src');
oImg.onload = function(){
$img.attr({
src:this.src,
isLoad:true
}).css('display','block')
oImg = null;
}
})
}
return{
init:function(){
//init css style
count = $slideList.length;
minL = -($slideList.length-1)*winW;
$wrapper.css('width',$slideList.length*winW);
$slideList.css('width',winW);
//lazy img
lazyImg();
$banner.on('touchstart',dragStart).on('touchmove',dragIng).on('touchend',dragEnd)
}
}
})()
bannerRender.init();
js实现在移动端图片轮播
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