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The toString() method returns a string representing the specified Error object.

Syntax

e.toString()

Return value

A string representing the specified Error object.

Description

The Error object overrides the Object.prototype.toString() method inherited by all objects. Its semantics are as follows (assuming Object and String have their original values):

Error.prototype.toString = function() {
  'use strict';

  var obj = Object(this);
  if (obj !== this) {
    throw new TypeError();
  }

  var name = this.name;
  name = (name === undefined) ? 'Error' : String(name);

  var msg = this.message;
  msg = (msg === undefined) ? '' : String(msg);

  if (name === '') {
    return msg;
  }
  if (msg === '') {
    return name;
  }

  return name + ': ' + msg;
};

Examples

var e = new Error('fatal error');
console.log(e.toString()); // 'Error: fatal error'

e.name = undefined;
console.log(e.toString()); // 'Error: fatal error'

e.name = '';
console.log(e.toString()); // 'fatal error'

e.message = undefined;
console.log(e.toString()); // 'Error'

e.name = 'hello';
console.log(e.toString()); // 'hello'

Specifications

Specification Status Comment
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.1.
ECMAScript 5.1 (ECMA-262)
The definition of 'Error.prototype.toString' in that specification.
Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Error.prototype.toString' in that specification.
Standard  
ECMAScript Latest Draft (ECMA-262)
The definition of 'Error.prototype.toString' in that specification.
Draft  

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Document Tags and Contributors

 Last updated by: jameshkramer,