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JS每日一题-小demo之JS实现通过键盘方向键操作图片上下左右无缝切换

JS每日一题-小demo之JS实现通过键盘方向键操作图片上下左右无缝切换

<!DOCTYPE html>  <html>  <head>  <meta charset="UTF-8">  <title>Document</title>  <style type="text/css">  .wrap {  margin: 150px auto;  position: relative;  width: 400px;  height: 300px;  overflow: hidden;  border: 2px solid #000;  }   .wrap img {  position: absolute;  }  </style>  </head>  <body>  <p>  <img src="pic/1.jpg" style="left:0;top:0" />  <img src="pic/2.jpg" style="left:0;top:100%" />  </p>  <script type="text/javascript" src="js/startmove.js?1.1.10"></script>  <script type="text/javascript">  (function(){  var data = ["pic/1.jpg","pic/2.jpg","pic/3.jpg","pic/4.jpg"];  var img = document.querySelectorAll('img');  var now = 0;  var next = 0;  var imgW = css(img[0],"width");  var imgH = css(img[0],"height");  var isMove = false;  document.addEventListener('keyup', function(e) {  if(isMove){  return;  }  switch(e.keyCode){  case 37:  //向左  toLeft();  break;  case 38:  //向上  toUp();  break;  case 39:  //向右  toRight();  break;  case 40:  //向下  toDown();  break;   }  });  function toLeft(){  next = (now + 1)%data.length;  init([0,0,0,imgW],{left:-imgW},{left:0});  }  function toUp(){  next = (now + 1)%data.length;  init([0,0,imgH,0],{top:-imgH},{top:0});  }  function toRight(){  next = (now - 1 + data.length)%data.length;  init([0,0,0,-imgW],{left:imgW},{left:0});  }  function toDown(){  next = (now - 1 + data.length)%data.length;  init([0,0,-imgH,0],{top:imgH},{top:0});  }  // styles = [0,0,0,0];  // target1 {}  //init 初始位置  function init(styles,target1,target2){  isMove = true;  img[0].src= data[now];  img[1].src= data[next];  css(img[0],"top",styles[0]);  css(img[0],"left",styles[1]);  css(img[1],"top",styles[2]);  css(img[1],"left",styles[3]);  now = next;  move(img[0],target1);  move(img[1],target2,function(){  isMove = false;  });  }  // 移动  function move(el,target,callBack){  startMove({  el:el,  target:target,  type: "easeOut",  time: 1000  });  }  })();   </script>  </body>  </html>  //动画形式公式  var Tween = {  linear: function (t, b, c, d){  return c*t/d + b;  },  easeIn: function(t, b, c, d){  return c*(t/=d)*t + b;  },  easeOut: function(t, b, c, d){  return -c *(t/=d)*(t-2) + b;  },  easeBoth: function(t, b, c, d){  if ((t/=d/2) < 1) {  return c/2*t*t + b;  }  return -c/2 * ((--t)*(t-2) - 1) + b;  },  easeInStrong: function(t, b, c, d){  return c*(t/=d)*t*t*t + b;  },  easeOutStrong: function(t, b, c, d){  return -c * ((t=t/d-1)*t*t*t - 1) + b;  },  easeBothStrong: function(t, b, c, d){  if ((t/=d/2) < 1) {  return c/2*t*t*t*t + b;  }  return -c/2 * ((t-=2)*t*t*t - 2) + b;  },  elasticIn: function(t, b, c, d, a, p){  if (t === 0) {   return b;   }  if ( (t /= d) == 1 ) {  return b+c;   }  if (!p) {  p=d*0.3;   }  if (!a || a < Math.abs(c)) {  a = c;   var s = p/4;  } else {  var s = p/(2*Math.PI) * Math.asin (c/a);  }  return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;  },  elasticOut: function(t, b, c, d, a, p){  if (t === 0) {  return b;  }  if ( (t /= d) == 1 ) {  return b+c;  }  if (!p) {  p=d*0.3;  }  if (!a || a < Math.abs(c)) {  a = c;  var s = p / 4;  } else {  var s = p/(2*Math.PI) * Math.asin (c/a);  }  return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;  },    elasticBoth: function(t, b, c, d, a, p){  if (t === 0) {  return b;  }  if ( (t /= d/2) == 2 ) {  return b+c;  }  if (!p) {  p = d*(0.3*1.5);  }  if ( !a || a < Math.abs(c) ) {  a = c;   var s = p/4;  }  else {  var s = p/(2*Math.PI) * Math.asin (c/a);  }  if (t < 1) {  return - 0.5*(a*Math.pow(2,10*(t-=1)) *   Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;  }  return a*Math.pow(2,-10*(t-=1)) *   Math.sin( (t*d-s)*(2*Math.PI)/p )*0.5 + c + b;  },  backIn: function(t, b, c, d, s){  if (typeof s == 'undefined') {    s = 1.70158;  }  return c*(t/=d)*t*((s+1)*t - s) + b;  },  backOut: function(t, b, c, d, s){  if (typeof s == 'undefined') {  s = 2.70158;  //回缩的距离  }  return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;  },   backBoth: function(t, b, c, d, s){  if (typeof s == 'undefined') {  s = 1.70158;   }  if ((t /= d/2 ) < 1) {  return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;  }  return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;  },  bounceIn: function(t, b, c, d){  return c - Tween['bounceOut'](d-t, 0, c, d) + b;  },        bounceOut: function(t, b, c, d){  if ((t/=d) < (1/2.75)) {  return c*(7.5625*t*t) + b;  } else if (t < (2/2.75)) {  return c*(7.5625*(t-=(1.5/2.75))*t + 0.75) + b;  } else if (t < (2.5/2.75)) {  return c*(7.5625*(t-=(2.25/2.75))*t + 0.9375) + b;  }  return c*(7.5625*(t-=(2.625/2.75))*t + 0.984375) + b;  },    bounceBoth: function(t, b, c, d){  if (t < d/2) {  return Tween['bounceIn'](t*2, 0, c, d) * 0.5 + b;  }  return Tween['bounceOut'](t*2-d, 0, c, d) * 0.5 + c*0.5 + b;  }  }  // 获取或者设置样式  function css(el,attr,val){  if(arguments.length == 2){  if(el.currentStyle){  val = el.currentStyle[attr];  } else {  val = getComputedStyle(el)[attr];  }  return parseFloat(val);  } else {  if(attr == "opacity"){  el.style.opacity = val;  el.style.filter = "alpha(opacity= "+val*100+")";  } else if(attr == "zIndex"){  el.style[attr] = Math.round(val);  }else {  el.style[attr] = val + "px";  }  }  }  //执行动画  function startMove(init){  clearInterval(init.el.timer);  var t = 0;   var b = {};  var c = {};  var d = init.time/20;  for( var s in init.target){   b[s] = css(init.el,s);  c[s] = init.target[s] - b[s];  }   init.el.timer = setInterval(function(){  t++;  if(t > d){  clearInterval(init.el.timer);  init.callBack&&init.callBack();  } else {  for(var s in init.target){  var val = Tween[init.type](t,b[s],c[s],d);  css(init.el,s,val);  }  }  },20);  }

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