/ Dropdown

React component for positioning an element aligned to another

React component for positioning an element aligned to another


This is a React component for anchoring a fixed position element, such as a dropdown menu, to the edge of an element on the page. The fixed position element will automatically be placed so that it fits on the screen if possible, and it will automatically reposition if needed when the user scrolls.

You can find its code in the example directory. The example may be compiled
by running:

yarn example-build

You can build the example with live editing enabled (using
react-transform-hmr and
browserify-hmr) by running:

yarn example-watch


This module exports the FloatAnchor React component, which takes the
following props:

  • anchor must be a single React Element. This element will be placed in the
    page where the FloatAnchor element was used, with no added wrapper elements
    around it.
  • float must be null or a single React Element. This element will be placed
    in a container div which has position:fixed styling, is attached directly
    to the document body, and is positioned to line up with the anchor element.
  • options is an optional object of options to control how the float element's
    container is aligned to the anchor element. The options are the same as those
    supported by contain-by-screen (version ^1.0).
  • zIndex is an optional number controlling the z-index CSS property of the
    float element's container.
  • floatContainerClassName is an optional string specifying a CSS class to
    apply to the float element's container div.

FloatAnchor has the following static methods:

  • parentNodes(node) takes a DOM node, and returns an iterator that yields the
    node and then each parentNode, unless the current node is a float element's
    container div, then its corresponding anchor DOM node will be yielded next
    instead. This is useful when you are listening to events from the entire page
    and need to determine whether an event's target is logically contained by a
    React component that has children that use FloatAnchor.

The FloatAnchor component has a reposition method, which you should call if
you change the size of the contents of the anchor or float elements.

The container div of the float element has its rfaAnchor property set to
be equal to the anchor DOM element.