ReferenceError

Class: ReferenceError

A subclass of Error that indicates that an attempt is being made to access a variable that is not defined. Such errors commonly indicate typos in code, or an otherwise broken program.

While client code may generate and propagate these errors, in practice, only V8 will do so.

doesNotExist;
  // throws ReferenceError, doesNotExist is not a variable in this program.

ReferenceError instances will have an error.arguments property whose value is an array containing a single element: a string representing the variable that was not defined.

const assert = require('assert');
try {
  doesNotExist;
} catch(err) {
  assert(err.arguments[0], 'doesNotExist');
}

Unless an application is dynamically generating and running code, ReferenceError instances should always be considered a bug in the code or its dependencies.