JavaScript 对象

 

 

JavaScript 对象

 

var h = document.documentElement.clientHeight,

mybody = document.getElementsByTagName(‘body’)[0];

mybody.style.height = h + ‘px’;

 

 

//返回角度

function GetSlideAngle(dx,dy) {

return Math.atan2(dy,dx) * 180 / Math.PI;

}

 

//根据起点和终点返回方向 1:向上,2:向下,3:向左,4:向右,0:未滑动

function GetSlideDirection(startX,startY, endX, endY) {

var dy = startY – endY;

var dx = endX – startX;

var result = 0;

 

//如果滑动距离太短

if (Math.abs(dx) < 2 && Math.abs(dy) < 2) {

return result;

}

var angle = GetSlideAngle(dx, dy);

if (angle >= -45 && angle < 45) {

result = 4;

}else if (angle >= 45 && angle < 135) {

result = 1;

}else if (angle >= -135 && angle < -45) {

result = 2;

}else if ((angle >= 135 && angle <= 180) || (angle >= -180 && angle < -135)) {

result = 3;

}

return result;

}

 

 

//滑动处理

var startX, startY;

mybody.addEventListener(‘touchstart’, function (ev){

ev.preventDefault();

startX = ev.touches[0].pageX;

startY = ev.touches[0].pageY;

}, false);

 

mybody.addEventListener(‘touchmove’, function (ev){

var endX, endY;

ev.preventDefault();

endX = ev.changedTouches[0].pageX;

endY = ev.changedTouches[0].pageY;

 

var direction = GetSlideDirection(startX, startY, endX, endY);

switch (direction){

case 0:

alert(“没滑动”);

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);

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