Error() constructor

The Error constructor creates an error object.

Syntax

new Error()
new Error(message)
new Error(message, options)
new Error(message, options, fileName)
new Error(message, options, fileName, lineNumber)

Parameters

message Optional

A human-readable description of the error.

options Optional

An object that has the following properties:

cause Optional

A property indicating the specific cause of the error. When catching and re-throwing an error with a more-specific or useful error message, this property should be used to pass the original error.

fileName Optional

The value for the fileName property on the created Error object. Defaults to the name of the file containing the code that called the Error() constructor.

lineNumber Optional

The value for the lineNumber property on the created Error object. Defaults to the line number containing the Error() constructor invocation.

Examples

Function call or new construction

When Error is used like a function -- without new, it will return an Error object. Therefore, a mere call to Error will produce the same output that constructing an Error object via the new keyword would.

// this...
const x = Error('I was created using a function call!')

// ...has the same functionality as this.
const y = new Error('I was constructed via the "new" keyword!')

Rethrowing an error with a cause

It is sometimes useful to catch an error and re-throw it with a new message. In this case you should pass the original error into the constructor for the new Error, as shown.

  try {
    frameworkThatCanThrow();
  } catch (err) {
    throw new Error('New error message', { cause: err });
  }

For a more detailed example see Error > Differentiate between similar errors.

Specifications

Specification
ECMAScript Language Specification (ECMAScript)
# sec-error-constructor

Browser compatibility

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See also