鼠标按住拖动

$(function() {

$(document).mousemove(function(e) {

if (!!this.move) {

var posix = !document.move_target ? {'x': 0, 'y': 0} : document.move_target.posix,

callback = document.call_down || function() {

$(this.move_target).css({

'top': e.pageY - posix.y,

'left': e.pageX - posix.x

});

};

callback.call(this, e, posix);

}

}).mouseup(function(e) {

if (!!this.move) {

var callback = document.call_up || function(){};

callback.call(this, e);

$.extend(this, {

'move': false,

'move_target': null,

'call_down': false,

'call_up': false

});

}

});

var $box = $('#box').mousedown(function(e) {

    var offset = $(this).offset();

    this.posix = { 'y': e.pageY - offset.top};

    $.extend(document, {'move': true, 'move_target': this});

});

});