JS Mobile Finger Swipe

varstartx, starty;

     //获得角度      function getAngle(angx, angy) {          return Math.atan2(angy, angx) * 180 / Math.PI;      };      //根据起点终点返回方向 1向上 2向下 3向左 4向右 0未滑动      function getDirection(startx, starty, endx, endy) {          var angx = endx - startx;          var angy = endy - starty;          var result = 0;          //如果滑动距离太短          if (Math.abs(angx) < 2 && Math.abs(angy) < 2) {              return result;          }          var angle = getAngle(angx, angy);          if (angle >= -135 && angle <= -45) {              result = 1;          }  else if (angle > 45 && angle < 135) {              result = 2;          }  else if ((angle >= 135 && angle <= 180) || (angle >= -180 && angle < -135)) {              result = 3;          }  else if (angle >= -45 && angle <= 45) {              result = 4;          }          return result;      }      //手指接触屏幕      document.addEventListener( "touchstart" , function(e) {          startx = e.touches[0].pageX;          starty = e.touches[0].pageY;      },  false );      //手指离开屏幕      document.addEventListener( "touchend" , function(e) {          var endx, endy;          endx = e.changedTouches[0].pageX;          endy = e.changedTouches[0].pageY;          var direction = getDirection(startx, starty, endx, endy);          switch (direction) {              case 0:                  alert( "未滑动！" );                  break ;              case 1:                  alert( "向上！" )                  break ;              case 2:                  alert( "向下！" )                  break ;              case 3:                  alert( "向左！" )                  break ;              case 4:                  alert( "向右！" )                  break ;              default :          }      },  false );

JS Mobile Finger Swipe