javascript移动设备Web开发中对touch事件的封装实例_javascript技巧

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 );