trotzig/diffux

define([
    "../core",
    "../manipulation" // appendTo
], function( jQuery ) {

var iframe,
    elemdisplay = {};

/**
 * Retrieve the actual display of a element
 * @param {String} name nodeName of the element
 * @param {Object} doc Document object
 */
// Called only from within defaultDisplay
function actualDisplay( name, doc ) {
    var style,
        elem = jQuery( doc.createElement( name ) ).appendTo( doc.body ),

        // getDefaultComputedStyle might be reliably used only on attached element
        display = window.getDefaultComputedStyle && ( style = window.getDefaultComputedStyle( elem[ 0 ] ) ) ?

            // Use of this method is a temporary fix (more like optimization) until something better comes along,
            // since it was removed from specification and supported only in FF
            style.display : jQuery.css( elem[ 0 ], "display" );

    // We don't have any data stored on the element,
    // so use "detach" method as fast way to get rid of the element
    elem.detach();

    return display;
}

/**
 * Try to determine the default display value of an element
 * @param {String} nodeName
 */
function defaultDisplay( nodeName ) {
    var doc = document,
        display = elemdisplay[ nodeName ];

    if ( !display ) {
        display = actualDisplay( nodeName, doc );

        // If the simple way fails, read from inside an iframe
        if ( display === "none" || !display ) {

            // Use the already-created iframe if possible
            iframe = (iframe || jQuery( "<iframe frameborder='0' width='0' height='0'/>" )).appendTo( doc.documentElement );

            // Always write a new HTML skeleton so Webkit and Firefox don't choke on reuse
            doc = iframe[ 0 ].contentDocument;

            // Support: IE
            doc.write();
            doc.close();

            display = actualDisplay( nodeName, doc );
            iframe.detach();
        }

        // Store the correct default display
        elemdisplay[ nodeName ] = display;
    }

    return display;
}

return defaultDisplay;

});