How control dragging only a side, such left side only by jqueryui drag?

$(".draggable").draggable({axis: 'x'});

<div 开发者_如何学Cclass="draggable">

I am draggable to left side only, and not right or up or down, the axis : x controls me to prevent up or down dragging, but make me not right too. Thanks

I solved it saving the previous left offset and comparing it with the new left offset.

var previousOffset = null;

$( "#draggable" ).draggable({
  axis: 'x',
  drag: function(event,ui){
    if(previousOffset == null)
       previousOffset = ui.offset.left;
    else{
      if(previousOffset < ui.offset.left)
        return false; 
      else
        previousOffset = ui.offset.left;
    }
  }
});

Here's working: http://jsbin.com/ubine3/2