Javascript(或其他一些语言)无需使用 pageYOffset 即可检测车轮方向

Question

我的页面不高于窗口 => 它没有滚动条。

如何检测车轮滚动的方向？

如果 JavaScript 无法处理这个问题，是否有其他网络语言可以帮助我解决这个问题？

谢谢

Answer 1

在 MDN page for "wheel" events 上批发给您，转载如下:

(function(window,document) {

    var prefix = "", _addEventListener, onwheel, support;

    // detect event model
    if ( window.addEventListener ) {
        _addEventListener = "addEventListener";
    } else {
        _addEventListener = "attachEvent";
        prefix = "on";
    }

    // detect available wheel event
    support = "onwheel" in document.createElement("div") ? "wheel" : // Modern browsers support "wheel"
              document.onmousewheel !== undefined ? "mousewheel" : // Webkit and IE support at least "mousewheel"
              "DOMMouseScroll"; // let's assume that remaining browsers are older Firefox

    window.addWheelListener = function( elem, callback, useCapture ) {
        _addWheelListener( elem, support, callback, useCapture );

        // handle MozMousePixelScroll in older Firefox
        if( support == "DOMMouseScroll" ) {
            _addWheelListener( elem, "MozMousePixelScroll", callback, useCapture );
        }
    };

    function _addWheelListener( elem, eventName, callback, useCapture ) {
        elem[ _addEventListener ]( prefix + eventName, support == "wheel" ? callback : function( originalEvent ) {
            !originalEvent && ( originalEvent = window.event );

            // create a normalized event object
            var event = {
                // keep a ref to the original event object
                originalEvent: originalEvent,
                target: originalEvent.target || originalEvent.srcElement,
                type: "wheel",
                deltaMode: originalEvent.type == "MozMousePixelScroll" ? 0 : 1,
                deltaX: 0,
                deltaZ: 0,
                preventDefault: function() {
                    originalEvent.preventDefault ?
                        originalEvent.preventDefault() :
                        originalEvent.returnValue = false;
                }
            };

            // calculate deltaY (and deltaX) according to the event
            if ( support == "mousewheel" ) {
                event.deltaY = - 1/40 * originalEvent.wheelDelta;
                // Webkit also support wheelDeltaX
                originalEvent.wheelDeltaX && ( event.deltaX = - 1/40 * originalEvent.wheelDeltaX );
            } else {
                event.deltaY = originalEvent.detail;
            }

            // it's time to fire the callback
            return callback( event );

        }, useCapture || false );
    }

})(window,document);

然后你可以:

addWheelListener( document, function( e ) { 
    console.log( e.deltaY < 0 ? "up" : "down" ); 
    e.preventDefault(); 
} );