TA貢獻1877條經驗 獲得超1個贊
function(wrap){
var wrap = document.getElementById(wrap);
var hoverDir = function(e){
var w = wrap.offsetWidth,
h = wrap.offsetHeight,
x = ( e.clientX - wrap.offsetLeft - ( w / 2 ) ) * ( w > h ? ( h / w ) : 1 ),
y = (e.clientY - wrap.offsetTop - (h / 2)) * (h > w ? (w / h) : 1),
// 上(0) 右(1) 下(2) 左(3)
direction = Math.round( ( ( ( Math.atan2( y, x ) * ( 180 / Math.PI ) ) + 180 ) / 90) + 3 ) % 4,
eventType = e.type,
dirName = new Array('上方','右側','下方','左側');
if( e.type == 'mouseover' || e.type == 'mouseenter' ){
wrap.innerHTML = dirName[direction] + '進入';
}else{
wrap.innerHTML = dirName[direction] + '離開';
}
}
if( window.addEventListener ){
wrap.addEventListener( 'mouseover',hoverDir,false );
wrap.addEventListener( 'mouseout',hoverDir,false );
}else if( window.attachEvent ){
wrap.attachEvent( 'onmouseenter',hoverDir );
wrap.attachEvent( 'onmouseleave',hoverDir );
}
}
這是通用的代碼，核心就是 Math.round( ( ( ( Math.atan2( y, x ) * ( 180 / Math.PI ) 原理我也不太清楚，然后就能返回四個值，就可判斷 四個方向。
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