getTaxonomyValue.js

/*
  Rest query example:
      var url = _spPageContextInfo.siteServerRelativeUrl + "/_api/web/lists/getbytitle('ListName')/items?";
      url = url + "&$expand=TaxCatchAll,FHI_Responsible";
      url = url + "&$select=*,TaxCatchAll/Term,TaxCatchAll/IdForTerm,TaxCatchAll/Term1033,TaxCatchAll/Term1044";
*/
  
  // usage 
  // getTaxonomyValue(listItem, field);

  /**
   * extracts Taxonomy field value from TaxCatchAll field.
   * listItem includes $select=TaxCatchAll/Term,TaxCatchAll/IdForTerm,TaxCatchAll/Term1033,TaxCatchAll/Term1044
   * @returns {String}
   * @param {ActivityList.Value} listItem SP ListItem in json;odata=nometadata format
   * @param {String} field SP Field internal name
   * 
   * @memberOf ActivityItems
   */
  function getTaxonomyValue(listItem, field) {
    if (!listItem[field]) return;

    var taxField: TaxField = listItem[field];
    var taxCatchAll = listItem.TaxCatchAll;

    var taxFieldInfo = taxCatchAll.find(tax => tax.IdForTerm === taxField.TermGuid);
    return taxFieldInfo['Term' + _spPageContextInfo.currentLanguage] || taxFieldInfo['Term']
  }