var api = this.getApi(),
cache = this.constructor.static.interwikiPrefixesPromiseCache,
key = api.defaults.ajax.url;
- if ( !cache.hasOwnProperty( key ) ) {
+ if ( !Object.prototype.hasOwnProperty.call( cache, key ) ) {
cache[ key ] = api.get( {
action: 'query',
meta: 'siteinfo',