mousewheel滚轮事件

/* 
 * 滚轮事件只有firefox比较特殊，使用DOMMouseScroll; 其他浏览器使用mousewheel;
 * 
*/
// firefox
document.body.addEventListener("DOMMouseScroll", function(event) {

    var direction= event.detail && (event.detail > 0 ? "mousedown" : "mouseup");
    console.log(direction);    
});

// chrome and ie
document.body.onmousewheel = function (event) {
    event = event || window.event;

    var direction = event.wheelDelta && (event.wheelDelta > 0 ? "mouseup" : "mousedown");
    console.log(direction);
};

// jquery 兼容的滚轮事件
$(document).on("mousewheel DOMMouseScroll", function (e) {
    
    var delta = (e.originalEvent.wheelDelta && (e.originalEvent.wheelDelta > 0 ? 1 : -1)) ||  // chrome & ie
                (e.originalEvent.detail && (e.originalEvent.detail > 0 ? -1 : 1));              // firefox

    
    if (delta > 0) {
        // 向上滚
        console.log("wheelup");
    } else if (delta < 0) {
        // 向下滚
        console.log("wheeldown");
    }
});