A set of helpers I use for Google Sheets.

GoogleSheetsHelpers.gs

/**
 * Retrieves the value associated with the variable from the “Base Variables” sheet.
 *
 * @param {string} variableName The variable to retrieve. The string must be the same as in the “Variable” column of the “Base Variables” sheet.
 * @return The input multiplied by 2.
 * @customfunction
 */
function getBaseVar(variableName) {
  // Get variables.
  var variableSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Base Variables");
  var variableKeyValuePairs = variableSheet.getRange('A2:B').getValues();
  
  // Remove empty variable pairs.
  variableKeyValuePairs = variableKeyValuePairs.filter(function(keyValuePair) {
    return (keyValuePair[0].length !== 0) && (keyValuePair[1].length !== 0);
  });
  
  // Find variable pair.
  variableKeyValuePairs = variableKeyValuePairs.filter(function(keyValuePair) {
    return keyValuePair[0] === variableName;
  });
  
  // Return: if there's nothing found, empty string, else return the found value.
  if (variableKeyValuePairs.length === 0) {
    return '';
  } else {
    return variableKeyValuePairs[0][1];
  }
}