jquery 拖拽移动插件

$(element).on('mousedown', function(event) {
    var startX = event.pageX;
    var startY = event.pageY;
    var initialX = parseInt($(this).css('left'), 10);
    var initialY = parseInt($(this).css('top'), 10);

    $(document).on('mousemove', function(event) {
        requestAnimationFrame(function() {
            var offsetX = event.pageX - startX;
            var offsetY = event.pageY - startY;
            $(element).css({
                transform: 'translate(' + (initialX + offsetX) + 'px, ' + (initialY + offsetY) + 'px)'
            });
        });
    });

    $(document).on('mouseup', function() {
        $(document).off('mousemove mouseup');
    });
});

$(document).on('mousemove', function(event) {
    var maxX = $(window).width() - $(element).outerWidth();
    var maxY = $(window).height() - $(element).outerHeight();
    var offsetX = Math.min(maxX, Math.max(0, event.pageX - startX));
    var offsetY = Math.min(maxY, Math.max(0, event.pageY - startY));
    $(element).css({
        transform: 'translate(' + offsetX + 'px, ' + offsetY + 'px)'
    });
});