type: utility

release: 1.8

status: released

documentation: http://api.jqueryui.com/position/ 

demo: http://jqueryui.com/position/

1 - Description:

Utility script for positioning any widget relative to the window, document, a particular element, or the pointer. This utility could be used on its own, but should also be used by all plugins that require positioning elements.  A few examples are:

• menus: (menu's left top at left bottom of menu button) A standard menu opens directly below the bottom left corner of the target and the menu itself would be aligned top left.
• tooltip: (tooltip's left bottom at center top of element/cursor) If the link or element is the target, you'd probably want to have the left edge of the tooltip centered horizontally above the element.  If a tooltip uses the current cursor position as the target, this will cause the tooltip to be place just above and to the right of the cursor, since a cursor occupies a single pixel.
• dialog: (dialog's center at window's center) A dialog usually is centered vertically and horizontally within the window. 

Positioning system:

We can use a simple system to define how the positioned element (e.g., menu or tooltip) should be placed in relation to the target element (e.g., link or button).

• The positioned element and target element both have 9 positions that map to the corners and centers of the objects.
• For these positions, we can use a CSS-style naming convention for horizontal (left, center, right) and vertical (top, center, bottom) values.

To describe the relationship between the target and positioned element, we can specify a pair of these positions: 

By combining the target and positioned elements together, we arrive at 81 possible positioning combinations.

Collision detection

• If the positioned object will not safely fit in the specified horizonal or vertical position, the positioned element can:
• flip to the opposite side.
• fit so the element stays in the desired direction, but is re-positioned so it is fully visible.
• flip and fit.
• not do collision detection.
• These collision detection options should be set independently for horizontal and vertical settings.
• A user/plugin can get the collision detection to re-run when the window is resized by simply calling the plugin again with the same options in a window resize event handler.

2 - Visual Design:

N/A

3 - Functional Specifications/Requirements: 

The element being positioned must support relative, absolute and fixed positioning.  If the element's position style is set to static, it will be set to relative when being positioned.

4 - Markup & Style:

N/A

5 - Latest version of plugin:

http://view.jqueryui.com/master/demos/position/default.html

6 - Open issues being discussed