Q:

possible to constrain jQuery resize to x or y axis, like drag constrain?

This jQuery lets you constrain drag movement so it occurs only on the axis specified:
$("#draggable2").draggable({ axis: 'x' });

See: http://jqueryui.com/demos/draggable/#constrain-movement
This is not legal jQuery but I wish it were:
$("#Container").resizable({ minHeight: 150, containment: {axis:'y' } });

Is it possible to prevent the user from making #Container wider while allowing her to make it taller?
Thanks

A:

Both of these answers work, but they have the unfortunate consequence of showing a <-> cursor over the eastern border, making the user think they might be able to resize the width. What I think is a better match is to call this on the jQuery object:
.resizable({handles:'s'})
since this will simply remove the possibility of changing the width, and the cursor. 

A:

Yes, it's possible by using UI events. Along the x-axis:
$("#Container").resizable({
    resize: function(event, ui) {
        ui.size.width = ui.originalSize.width;
    }
});

or along the y-axis:
$("#Container").resizable({
    resize: function(event, ui) {
        ui.size.height = ui.originalSize.height;
    }
});

A:

I found that just clearing on the height or width inline style on the object on resize also works. It also has the added benefit of not being bound to the object's original dimensions (since those could change based on the contents)
$("#Container").resizable({
    resize: function(event, ui) {
        $(this).css('height','');
    }
});

