Function internalData

docs/welcome/js/jquery.js:1551–1643

( elem, name, data, pvt /* Internal Use Only */ )

    rmultiDash = /([A-Z])/g;

function internalData( elem, name, data, pvt /* Internal Use Only */ ){
    if ( !jQuery.acceptData( elem ) ) {
        return;
    }

    var thisCache, ret,
        internalKey = jQuery.expando,
        getByName = typeof name === "string",

        // We have to handle DOM nodes and JS objects differently because IE6-7
        // can't GC object references properly across the DOM-JS boundary
        isNode = elem.nodeType,

        // Only DOM nodes need the global jQuery cache; JS object data is
        // attached directly to the object so GC can occur automatically
        cache = isNode ? jQuery.cache : elem,

        // Only defining an ID for JS objects if its cache already exists allows
        // the code to shortcut on the same path as a DOM node with no cache
        id = isNode ? elem[ internalKey ] : elem[ internalKey ] && internalKey;

    // Avoid doing any more work than we need to when trying to get data on an
    // object that has no data at all
    if ( (!id || !cache[id] || (!pvt && !cache[id].data)) && getByName && data === undefined ) {
        return;
    }

    if ( !id ) {
        // Only DOM nodes need a new unique ID for each element since their data
        // ends up in the global cache
        if ( isNode ) {
            elem[ internalKey ] = id = core_deletedIds.pop() || jQuery.guid++;
        } else {
            id = internalKey;
        }
    }

    if ( !cache[ id ] ) {
        cache[ id ] = {};

        // Avoids exposing jQuery metadata on plain JS objects when the object
        // is serialized using JSON.stringify
        if ( !isNode ) {
            cache[ id ].toJSON = jQuery.noop;
        }
    }

    // An object can be passed to jQuery.data instead of a key/value pair; this gets
    // shallow copied over onto the existing cache
    if ( typeof name === "object" || typeof name === "function" ) {
        if ( pvt ) {
            cache[ id ] = jQuery.extend( cache[ id ], name );
        } else {
            cache[ id ].data = jQuery.extend( cache[ id ].data, name );
        }
    }

    thisCache = cache[ id ];