Forge Viewer function to separate host or linked elements in the composite Revit model

separateHostOrLinkedElements.js

function getLeafNodes( model, dbIds ) {

      return new Promise( ( resolve, reject ) => {

        try {

          const instanceTree = model.getData().instanceTree

          dbIds = dbIds || instanceTree.getRootId();

          const dbIdArray = Array.isArray( dbIds ) ? dbIds : [dbIds]
          let leafIds = [];

          const getLeafNodesRec = ( id ) => {
            let childCount = 0;

            instanceTree.enumNodeChildren( id, ( childId ) => {
                getLeafNodesRec( childId );

                ++childCount;
              })

            if( childCount == 0 ) {
              leafIds.push( id );
            }
          }

          for( let i = 0; i < dbIdArray.length; ++i ) {
            getLeafNodesRec( dbIdArray[i] );
          }

          return resolve( leafIds );

        } catch (ex) {

          return reject(ex)
        }
    })
}


function userFunction( pdb, dbIds ) {
    const idsLoaded = pdb.externalIdsLoaded();
    if( !idsLoaded )
        return null;

    const hostElemetns = [], linkedElements = [];
    const idsMap = pdb.getExternalIdMapping();
    const ids = Object.keys( idsMap );

    for( let i = 0; i < dbIds.length; i++ ) {
        const dbId = dbIds[i];
        const externalId = pdb.getIdAt( dbId );

        if( externalId.lastIndexOf( '/' ) !== -1 ) {
            linkedElements.push( dbId );
        } else {
            hostElemetns.push( dbId );
        }
    }

    return {
        hostElemetns,
        linkedElements
    };
}

await viewer.model.getPropertyDb().executeUserFunction( userFunction, await getLeafNodes() )