javascript移动设备Web开发中对touch事件的封装实例

element.addEventListener( 'touchstart', function( e ){
  var touches = e.touches[0];

  startTx = touches.clientX;
  startTy = touches.clientY;
}, false );

element.addEventListener( 'touchend', function( e ){
  var touches = e.changedTouches[0],
    endTx = touches.clientX,
    endTy = touches.clientY;

  // 在部分设备上 touch 事件比较灵敏，导致按下和松开手指时的事件坐标会出现一点点变化
  if( Math.abs(startTx - endTx) < 6 && Math.abs(startTy - endTy) < 6 ){
    console.log( 'fire tap event' );
  }
}, false );

element.addEventListener( 'touchstart', function( e ){
  if( dTapTimer ){
    clearTimeout( dTapTimer );
    dTapTimer = null;
  }

  var touches = e.touches[0];

  startTx = touches.clientX;
  startTy = touches.clientY;  
}, false );

element.addEventListener( 'touchend', function( e ){
  var touches = e.changedTouches[0],
    endTx = touches.clientX,
    endTy = touches.clientY,
    now = Date.now(),
    duration = now - lastTime;

  // 首先要确保能触发单次的 tap 事件
  if( Math.abs(startTx - endTx) < 6 && Math.abs(startTx - endTx) < 6 ){
    // 两次 tap 的间隔确保在 500 毫秒以内
    if( duration < 301 ){
      // 本次的 tap 位置和上一次的 tap 的位置允许一定范围内的误差
      if( lastTx !== null &&
        Math.abs(lastTx - endTx) < 45 &&
        Math.abs(lastTy - endTy) < 45 ){

        firstTouchEnd = true;
        lastTx = lastTy = null;
        console.log( 'fire double tap event' );
      }
    }
    else{
      lastTx = endTx;
      lastTy = endTy;
    }
  }
  else{
    firstTouchEnd = true;
    lastTx = lastTy = null;
  }

  lastTime = now;
}, false );

// 在 iOS 的 safari 上手指敲击屏幕的速度过快，
// 有一定的几率会导致第二次不会响应 touchstart 和 touchend 事件
// 同时手指长时间的touch不会触发click

if( ~navigator.userAgent.toLowerCase().indexOf('iphone os') ){

  body.addEventListener( 'touchstart', function( e ){
      startTime = Date.now();
  }, true );

  body.addEventListener( 'touchend', function( e ){
      var noLongTap = Date.now() - startTime < 501;

      if( firstTouchEnd ){
          firstTouchEnd = false;
          if( noLongTap && e.target === element ){
              dTapTimer = setTimeout(function(){
                  firstTouchEnd = true;
                  lastTx = lastTy = null;
                  console.log( 'fire double tap event' );
              }, 400 );
          }
      }
      else{
          firstTouchEnd = true;
      }
  }, true );

// iOS 上手指多次敲击屏幕时的速度过快不会触发 click 事件
element.addEventListener( 'click', function( e ){
  if( dTapTimer ){
    clearTimeout( dTapTimer );
    dTapTimer = null;
    firstTouchEnd = true;
  }
}, false );

}

element.addEventListener( 'touchstart', function( e ){
  if( lTapTimer ){
    clearTimeout( lTapTimer );
    lTapTimer = null;
  }

  var touches = e.touches[0];

  startTx = touches.clientX;
  startTy = touches.clientY;

  lTapTimer = setTimeout(function(){
    console.log( 'fire long tap event' );
  }, 1000 );

  e.preventDefault();
}, false );

element.addEventListener( 'touchmove', function( e ){
  var touches = e.touches[0],
    endTx = touches.clientX,
    endTy = touches.clientY;

  if( lTapTimer && (Math.abs(endTx - startTx) > 5 || Math.abs(endTy - startTy) > 5) ){
    clearTimeout( lTapTimer );
    lTapTimer = null;
  }
}, false );

element.addEventListener( 'touchend', function( e ){
  if( lTapTimer ){
    clearTimeout( lTapTimer );
    lTapTimer = null;
  }
}, false );

element.addEventListener( 'touchstart', function( e ){
  var touches = e.touches[0];

  startTx = touches.clientX;
  startTy = touches.clientY;
  isTouchMove = false;
}, false );

element.addEventListener( 'touchmove', function( e ){
  isTouchMove = true;
  e.preventDefault();
}, false );

element.addEventListener( 'touchend', function( e ){
  if( !isTouchMove ){
    return;
  }

  var touches = e.changedTouches[0],
    endTx = touches.clientX,
    endTy = touches.clientY,
    distanceX = startTx - endTx
    distanceY = startTy - endTy,
    isSwipe = false;

  if( Math.abs(distanceX) >= Math.abs(distanceY) ){
    if( distanceX > 20 ){
      console.log( 'fire swipe left event' );
      isSwipe = true;
    }
    else if( distanceX < -20 ){
      console.log( 'fire swipe right event' );   
      isSwipe = true;
    }
  }
  else{
    if( distanceY > 20 ){
      console.log( 'fire swipe up event' );       
      isSwipe = true;
    }
    else if( distanceY < -20 ){
      console.log( 'fire swipe down event' );        
      isSwipe = true;
    }
  }

  if( isSwipe ){
    console.log( 'fire swipe event' );
  }
}, false );