toJSON

Returns a JSON representation of an error object.

Installation

$ npm install utils-error-to-json

Usage

var toJSON = require( 'utils-error-to-json' );

toJSON()

Returns a JSON representation of an error object.

var err = new Error( 'beep' );

var json = toJSON( err );
/*
  {
	"type": "Error",
	"name": "Error", // if present
	"message": "beep",
	"stack": "<stack>" // if present
  }
*/

The JSON object is guaranteed to have the following properties:

• type: error type
• message: error message

The only standardized cross-platform property is message. Depending on the platform, the following properties may be present:

• name: error name
• stack: stack trace
• code: error code (Node.js system errors)
• errno: error code string (Node.js system errors)
• syscall: string representing the failed system call (Node.js system errors)

The function also serializes all enumerable properties.

var err = new Error( 'beep' );
err.a = 'b';
err.c = { 'd': 'e' };

var json = toJSON( err );
/*
  {
	"type": "Error",
	"name": "Error", // if present
	"message": "beep",
	"stack": "<stack>", // if present
	"a": "b",
	"c": {
      "d": "e"
    }
  }
*/

Notes

• Supported built-in error types:

  • Error
  • TypeError
  • SyntaxError
  • ReferenceError
  • RangeError
  • URIError
  • EvalError

• The implementation supports custom error types and sets the type field to the closest built-in error type.

  function CustomError( msg ) {
  	this.name = 'CustomError';
  	this.message = msg || '';
  	this.stack = ( new TypeError() ).stack;
  	return this;
  }
  CustomError.prototype = Object.create( TypeError.prototype );
  CustomError.prototype.constructor = CustomError;
  
  var err = new CustomError( 'boop' );
  
  var json = toJSON( err );
  /*
    {
      "type": "TypeError",
      "name": "CustomError", 
      "message": "boop",
      "stack": "<stack>"
    }
  */

Examples

var toJSON = require( 'utils-error-to-json' );

var err = new Error( 'beep' );
console.log( toJSON( err ) );
/*
  {
	"type": "Error",
	"name": "Error",
	"message": "beep",
	"stack": "<stack>"
  }
*/

err = new TypeError( 'invalid type' );
console.log( toJSON( err ) );
/*
  {
	"type": "TypeError",
	"name": "TypeError",
	"message": "invalid type",
	"stack": "<stack>"
  }
*/

err = new SyntaxError( 'bad syntax' );
console.log( toJSON( err ) );
/*
  {
	"type": "SyntaxError",
	"name": "SyntaxError",
	"message": "bad syntax",
	"stack": "<stack>"
  }
*/

err = new ReferenceError( 'unknown variable' );
console.log( toJSON( err ) );
/*
  {
	"type": "ReferenceError",
	"name": "ReferenceError",
	"message": "unknown variable",
	"stack": "<stack>"
  }
*/

err = new URIError( 'bad URI' );
console.log( toJSON( err ) );
/*
  {
	"type": "URIError",
	"name": "URIError",
	"message": "bad URI",
	"stack": "<stack>"
  }
*/

err = new RangeError( 'value out-of-range' );
console.log( toJSON( err ) );
/*
  {
	"type": "RangeError",
	"name": "RangeError",
	"message": "value out-of-range",
	"stack": "<stack>"
  }
*/

err = new EvalError( 'eval error' );
console.log( toJSON( err ) );
/*
  {
	"type": "EvalError",
	"name": "EvalError",
	"message": "eval error",
	"stack": "<stack>"
  }
*/

To run the example code from the top-level application directory,

$ node ./examples/index.js

Tests

Unit

This repository uses tape for unit tests. To run the tests, execute the following command in the top-level application directory:

$ make test

All new feature development should have corresponding unit tests to validate correct functionality.

Test Coverage

This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:

$ make test-cov

Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,

$ make view-cov

Browser Support

This repository uses Testling for browser testing. To run the tests in a (headless) local web browser, execute the following command in the top-level application directory:

$ make test-browsers

To view the tests in a local web browser,

$ make view-browser-tests

License

MIT license.

Copyright

Copyright © 2015. Athan Reines.