Client-side (in-browser) import of Wikidata entities into another Wikibase installation

import.js

async function importEntitiesFromWikidata( wikidataEntityIds ) {
  const params = new URLSearchParams();
  params.set( 'action', 'wbgetentities' );
  params.set( 'ids', wikidataEntityIds.join( '|' ) );
  params.set( 'props', [ 'labels', 'descriptions', 'aliases', 'datatype' ].join( '|' ) );
  params.set( 'format', 'json' );
  params.set( 'origin', '*' );
  const response = await fetch( `https://www.wikidata.org/w/api.php?${ params.toString() }` ),
        json = await response.json();
  for ( const wikidataEntityData of Object.values( json.entities ) ) {
    await importEntityFromJson( wikidataEntityData );
  }
}

async function importEntityFromJson( wikidataEntityData ) {
  const wikidataEntityId = wikidataEntityData.id,
        api = new mw.Api();
  delete wikidataEntityData.id;
  for ( const key of [ 'labels', 'descriptions', 'aliases' ] ) {
    if ( key in wikidataEntityData ) {
      filterUnknownLanguages( wikidataEntityData[ key ] );
    }
  }
  try {
    await api.postWithEditToken( {
      action: 'wbeditentity',
      new: wikidataEntityData.type,
      data: JSON.stringify( wikidataEntityData ),
      summary: `Imported from ${ wikidataEntityId } on Wikidata`,
      bot: true,
    } );
  } catch ( e ) {
    if ( e === 'modification-failed' ) {
      return; // ignore; entity exists already
    } else {
      throw e;
    }
  }
}

function filterUnknownLanguages( terms ) {
  // InitialiseSettings.php, wmgExtraLanguageNames
  delete terms.kea;
  delete terms.nod;
  delete terms.nys;
  delete terms.ota;
  delete terms.rwr;
  delete terms.sje;
  delete terms.smj;
  delete terms.smn;
  delete terms.sms;
  delete terms.srq;
}

For example, to import all the allowed “sex or gender” values, I used:

importEntitiesFromWikidata( [
  "Q6581097",
  "Q6581072",
  "Q1097630",
  "Q303479",
  "Q189125",
  "Q1052281",
  "Q2449503",
  "Q48270",
  "Q1399232",
  "Q3277905",
  "Q746411",
  "Q350374",
  "Q660882",
  "Q44148",
  "Q43445",
  "Q207959",
  "Q301702",
  "Q27679766",
  "Q27679684",
  "Q3177577",
  "Q28873047",
  "Q505371",
  "Q52261234",
  "Q18116794",
  "Q1289754",
  "Q179294"
] ).then( console.log, console.error )

The list of IDs was generated by the snippet

ids = []; for ( const node of temp0.querySelectorAll('a[title^=Q]') ) { ids.push( node.title ); }; console.log( ids )

on https://www.wikidata.org/wiki/Property:P21, where temp0 was the wikibase-snaklistview-listview element selected in the Inspector.