ng-flush

A simple attribute directive that will flush an element to the bottom of its closest positioned parent (typically the window).

This is not to be confused with a sticky footer, which is easy to implement using CSS.

It is available through NPM:

npm install ng-flush

Usage

Check out the fiddle!

Include flush.min.js in your build or directly with a <script> tag and require the module in your module definition:

angular  
    .module('App', [  
        'flush',  
        ... // other dependencies  
    ]);

To flush an element to the bottom of its closest positioned parent:

<footer flush></footer>

The directive's approach is to set the following inline styles if the element does not naturally reach the bottom:

{
    position: 'absolute';  
    bottom: 0;
}

This means that the element will be flushed to the bottom of its closest positioned parent, regardless of whether it is the window or another element.

The directive will remove the flush styles if the bottom edge of the flushed element would naturally lie below the bottom edge of the parent, meaning that this is not a "sticky footer" (which could be done without JavaScript, using CSS). If the content of the parent is large enough to push the flushed element to the bottom its visible area, the flushed element will position itself naturally.

Typically this is best-used on an element which is the last visible child of its closest positioned parent. Otherwise, the children would appear to the user to change order when the flush is toggled - it would be below its siblings when flushed, and among its siblings when positioned naturally.

Flush triggers

The directive watches the scrollHeight and offsetHeight of the closest positioned parent. If either value changes, the element will be re-flushed.

Note that the directive attempts to use requestAnimationFrame or its browser-specific variants (if they are available) to watch the height values of the parent. This is because using $scope.$watch to keep an eye on the height is not fast enough to catch changes during animations, e.g. expansion and collapse of content within the parent. As a result, there is a slight visual delay when animations cause the parent to change size when $scope.$watch is used. However, since many browsers still do not implement requestAnimationFrame or an equivalent, the directive falls back gracefully and uses $scope.$watch instead when animation functions are not available.