JS Daily Question - A small demo using JS to achieve seamless switching of images up, down, left, and right through keyboard arrow keys

      
  
   
     //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); }