chamilo-lms2/app/Resources/public/assets/modernizr/feature-detects/css-positionsticky.js

// Sticky positioning - constrains an element to be positioned inside the
// intersection of its container box, and the viewport.
Modernizr.addTest('csspositionsticky', function () {

    var prop = 'position:';
    var value = 'sticky';
    var el = document.createElement('modernizr');
    var mStyle = el.style;

    mStyle.cssText = prop + Modernizr._prefixes.join(value + ';' + prop).slice(0, -prop.length);

    return mStyle.position.indexOf(value) !== -1;
});