wikimedia/mediawiki-extensions-Wikibase

/**
 * @module wikibase.entityPage.entityLoaded
 * @fires "wikibase.entityPage.entityLoaded"
 *
 * This module fires a MediaWiki hook named "wikibase.entityPage.entityLoaded" as soon as the JSON
 * representing the entity stored on the current entity page is loaded. Listener callbacks should
 * expect the entity as a native JavaScript object (the parsed JSON serialization) passed as the
 * first argument.
 *
 * Note: The entity object is completely frozen (read-only) to avoid the case when one of clients
 *       accidentally change it and break other clients.
 *
 * @example <caption>Basic usage</caption>
 * mw.hook( 'wikibase.entityPage.entityLoaded' ).add( function ( entity ) {
 *     'use strict';
 *     // Your code goes here
 *     console.log( entity );
 * } );
 *
 * @example <caption>Convert to jQuery promise</caption>
 * const entityPromise = $.Deferred( function ( deferred ) {
 *     mw.hook( 'wikibase.entityPage.entityLoaded' ).add( function ( entity ) {
 *         deferred.resolve( entity );
 *     } );
 * } ).promise();
 *
 * @example <caption>Convert to native promise</caption>
 * const entityPromise = new Promise( function ( resolve ) {
 *     mw.hook( 'wikibase.entityPage.entityLoaded' ).add( function ( entity ) {
 *         resolve( entity );
 *     } );
 * } );
 */
( function ( mwConfig ) {
    'use strict';

    /**
     * Copied from https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze
     *
     * @param {Object} obj
     * @return {Object}
     */
    function deepFreeze( obj ) {
        // Retrieve the property names defined on obj
        const propNames = Object.getOwnPropertyNames( obj );

        // Freeze properties before freezing self
        propNames.forEach( function ( name ) {
            const prop = obj[ name ];

            // Freeze prop if it is an object
            if ( typeof prop === 'object' && prop !== null ) {
                deepFreeze( prop );
            }
        } );

        // Freeze self (no-op if already frozen)
        return Object.freeze( obj );
    }

    const entityId = mwConfig.get( 'wbEntityId' );

    if ( entityId === null ) {
        mw.log.error(
            'wikibase.entityPage.entityLoaded should only be loaded ' +
            'in conjunction with the right JS config (e.g. ParserOutputJsConfigBuilder)!'
        );
        return;
    }

    // Load from Special:EntityData because it gets cached in several layers
    const specialEntityDataPath = mwConfig.get( 'wgArticlePath' ).replace(
        /\$1/g, 'Special:EntityData/' + entityId + '.json'
    );
    const url = new URL( specialEntityDataPath, location.href );
    url.searchParams.set( 'revision', mwConfig.get( 'wgRevisionId' ) );

    $.getJSON( url.toString(), ( data ) => {
        if ( !data || !data.entities || !data.entities[ entityId ] ) {
            return;
        }

        const wbEntity = data.entities[ entityId ];

        if ( wbEntity ) {
            // Note this assumes "wbEntity" contains valid JSON, and will throw an error otherwise.
            mw.hook( 'wikibase.entityPage.entityLoaded' ).fire( deepFreeze( wbEntity ) );
        }
    } );

}( mw.config ) );