Web/JavaScript/Reference/Global objects/Error

Error objects are thrown when runtime errors occur. The Error object can also be used as a base object for user-defined exceptions. See below for standard built-in error types.

Description

Runtime errors result in new Error objects being created and thrown.

Error types

Besides the generic Error constructor, there are other core error constructors in JavaScript. For client-side exceptions, see Exception handling statements.

EvalError: Creates an instance representing an error that occurs regarding the global function eval().
RangeError: Creates an instance representing an error that occurs when a numeric variable or parameter is outside of its valid range.
ReferenceError: Creates an instance representing an error that occurs when de-referencing an invalid reference.
SyntaxError: Creates an instance representing a syntax error.
TypeError: Creates an instance representing an error that occurs when a variable or parameter is not of a valid type.
URIError: Creates an instance representing an error that occurs when encodeURI() or decodeURI() are passed invalid parameters.
AggregateError: Creates an instance representing several errors wrapped in a single error when multiple errors need to be reported by an operation, for example by Promise.any().
InternalError ': Creates an instance representing an error that occurs when an internal error in the JavaScript engine is thrown. E.g. "too much recursion".

Constructor

Error(): Creates a new Error object.

Static methods

Error.captureStackTrace(): A non-standard V8 function that creates the stack property on an Error instance.

Instance properties

Error.prototype.message: Error message.
Error.prototype.name: Error name.
Error.prototype.description: A non-standard Microsoft property for the error description. Similar to message.
Error.prototype.number: A non-standard Microsoft property for an error number.
Error.prototype.fileName: A non-standard Mozilla property for the path to the file that raised this error.
Error.prototype.lineNumber: A non-standard Mozilla property for the line number in the file that raised this error.
Error.prototype.columnNumber: A non-standard Mozilla property for the column number in the line that raised this error.
Error.prototype.stack: A non-standard Mozilla property for a stack trace.

Instance methods

Error.prototype.toString(): Returns a string representing the specified object. Overrides the Object.prototype.toString() method.

Examples

Throwing a generic error

Usually you create an Error object with the intention of raising it using the throw keyword. You can handle the error using the try...catch construct:

try {
  throw new Error('Whoops!')
} catch (e) {
  console.error(e.name + ': ' + e.message)
}

Handling a specific error

You can choose to handle only specific error types by testing the error type with the error's constructor property or, if you're writing for modern JavaScript engines, instanceof keyword:

try {
  foo.bar()
} catch (e) {
  if (e instanceof EvalError) {
    console.error(e.name + ': ' + e.message)
  } else if (e instanceof RangeError) {
    console.error(e.name + ': ' + e.message)
  }
  // ... etc
}

Custom Error Types

You might want to define your own error types deriving from Error to be able to throw new MyError() and use instanceof MyError to check the kind of error in the exception handler. This results in cleaner and more consistent error handling code.

See "What's a good way to extend Error in JavaScript?" on StackOverflow for an in-depth discussion.

ES6 Custom Error Class

Versions of Babel prior to 7 can handle CustomError class methods, but only when they are declared with Object.defineProperty(). Otherwise, old versions of Babel and other transpilers will not correctly handle the following code without additional configuration.

Some browsers include the CustomError constructor in the stack trace when using ES2015 classes.

class CustomError extends Error {
  constructor(foo = 'bar', ...params) {
    // Pass remaining arguments (including vendor specific ones) to parent constructor
    super(...params)

    // Maintains proper stack trace for where our error was thrown (only available on V8)
    if (Error.captureStackTrace) {
      Error.captureStackTrace(this, CustomError)
    }

    this.name = 'CustomError'
    // Custom debugging information
    this.foo = foo
    this.date = new Date()
  }
}

try {
  throw new CustomError('baz', 'bazMessage')
} catch(e) {
  console.error(e.name)    //CustomError
  console.error(e.foo)     //baz
  console.error(e.message) //bazMessage
  console.error(e.stack)   //stacktrace
}

ES5 Custom Error Object

All browsers include the CustomError constructor in the stack trace when using a prototypal declaration.

function CustomError(foo, message, fileName, lineNumber) {
  var instance = new Error(message, fileName, lineNumber);
  instance.name = 'CustomError';
  instance.foo = foo;
  Object.setPrototypeOf(instance, Object.getPrototypeOf(this));
  if (Error.captureStackTrace) {
    Error.captureStackTrace(instance, CustomError);
  }
  return instance;
}

CustomError.prototype = Object.create(Error.prototype, {
  constructor: {
    value: Error,
    enumerable: false,
    writable: true,
    configurable: true
  }
});

if (Object.setPrototypeOf){
  Object.setPrototypeOf(CustomError, Error);
} else {
  CustomError.__proto__ = Error;
}

try {
  throw new CustomError('baz', 'bazMessage');
} catch(e){
  console.error(e.name); //CustomError
  console.error(e.foo); //baz
  console.error(e.message); //bazMessage
}

Specifications

Specification
ECMAScript (ECMA-262)The definition of 'Error' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`Error`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 6	Opera Full support 4	Safari Full support 1	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100
`Error()` constructor	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 6	Opera Full support 4	Safari Full support 1	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100
`columnNumber` Non-standard'	Chrome No support No	Edge No support No	Firefox Full support 1	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android Full support 4	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No	nodejs No support No
`fileName` Non-standard'	Chrome No support No	Edge No support No	Firefox Full support 1	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android Full support 4	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No	nodejs No support No
`lineNumber` Non-standard'	Chrome No support No	Edge No support No	Firefox Full support 1	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android Full support 4	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No	nodejs No support No
`message`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 6	Opera Full support 5	Safari Full support 1	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100
`name`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 6	Opera Full support 4	Safari Full support 1	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100
`stack` Non-standard'	Chrome Full support 3	Edge Full support 12	Firefox Full support 1	IE Full support 10	Opera Full support 10.5	Safari Full support 6	WebView Android Full support ≤37	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 11	Safari iOS Full support 6	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100
`toSource` Non-standard'	Chrome No support No	Edge No support No	Firefox No support 1 — 74 Notes' No support 1 — 74 Notes' Notes' Starting in Firefox 74, `toSource()` is no longer available for use by web content. It is still allowed for internal and privileged code.	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android Full support 4	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No	nodejs No support No
`toString`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 6	Opera Full support 4	Safari Full support 1	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100

Legend

Full support: Full support
No support: No support
Non-standard. Expect poor cross-browser support.': Non-standard. Expect poor cross-browser support.
See implementation notes.': See implementation notes.