<h1 align=center> <a href="http://chaijs.com" title="Chai Documentation"> <img alt="ChaiJS" src="http://chaijs.com/img/chai-logo.png"/> check-error </a> </h1> <p align=center> Error comparison and information related utility for <a href="http://nodejs.org">node</a> and the browser. </p> <p align=center> <a href="./LICENSE"> <img alt="license:mit" src="https://img.shields.io/badge/license-mit-green.svg?style=flat-square" /> </a> <a href="https://github.com/chaijs/check-error/releases"> <img alt="tag:?" src="https://img.shields.io/github/tag/chaijs/check-error.svg?style=flat-square" /> </a> <a href="https://travis-ci.org/chaijs/check-error"> <img alt="build:?" src="https://img.shields.io/travis/chaijs/check-error/master.svg?style=flat-square" /> </a> <a href="https://coveralls.io/r/chaijs/check-error"> <img alt="coverage:?" src="https://img.shields.io/coveralls/chaijs/check-error/master.svg?style=flat-square" /> </a> <a href="https://www.npmjs.com/packages/check-error"> <img alt="npm:?" src="https://img.shields.io/npm/v/check-error.svg?style=flat-square" /> </a> <a href="https://www.npmjs.com/packages/check-error"> <img alt="dependencies:?" src="https://img.shields.io/npm/dm/check-error.svg?style=flat-square" /> </a> <a href=""> <img alt="devDependencies:?" src="https://img.shields.io/david/chaijs/check-error.svg?style=flat-square" /> </a> <br/> <a href="https://saucelabs.com/u/chaijs-check-error"> <img alt="Selenium Test Status" src="https://saucelabs.com/browser-matrix/chaijs-check-error.svg" /> </a> <br> <a href="https://chai-slack.herokuapp.com/"> <img alt="Join the Slack chat" src="https://img.shields.io/badge/slack-join%20chat-E2206F.svg?style=flat-square" /> </a> <a href="https://gitter.im/chaijs/chai"> <img alt="Join the Gitter chat" src="https://img.shields.io/badge/gitter-join%20chat-D0104D.svg?style=flat-square" /> </a> </p> ## What is Check-Error? Check-Error is a module which you can use to retrieve an Error's information such as its `message` or `constructor` name and also to check whether two Errors are compatible based on their messages, constructors or even instances. ## Installation ### Node.js `check-error` is available on [npm](http://npmjs.org). To install it, type: $ npm install check-error ### Browsers You can also use it within the browser; install via npm and use the `check-error.js` file found within the download. For example: ```html <script src="./node_modules/check-error/check-error.js"></script> ``` ## Usage The primary export of `check-error` is an object which has the following methods: * `compatibleInstance(err, errorLike)` - Checks if an error is compatible with another `errorLike` object. If `errorLike` is an error instance we do a strict comparison, otherwise we return `false` by default, because instances of objects can only be compatible if they're both error instances. * `compatibleConstructor(err, errorLike)` - Checks if an error's constructor is compatible with another `errorLike` object. If `err` has the same constructor as `errorLike` or if `err` is an instance of `errorLike`. * `compatibleMessage(err, errMatcher)` - Checks if an error message is compatible with an `errMatcher` RegExp or String (we check if the message contains the String). * `getConstructorName(errorLike)` - Retrieves the name of a constructor, an error's constructor or `errorLike` itself if it's not an error instance or constructor. * `getMessage(err)` - Retrieves the message of an error or `err` itself if it's a String. If `err` or `err.message` is undefined we return an empty String. ```js var checkError = require('check-error'); ``` #### .compatibleInstance(err, errorLike) ```js var checkError = require('check-error'); var funcThatThrows = function() { throw new TypeError('I am a TypeError') }; var caughtErr; try { funcThatThrows(); } catch(e) { caughtErr = e; } var sameInstance = caughtErr; checkError.compatibleInstance(caughtErr, sameInstance); // true checkError.compatibleInstance(caughtErr, new TypeError('Another error')); // false ``` #### .compatibleConstructor(err, errorLike) ```js var checkError = require('check-error'); var funcThatThrows = function() { throw new TypeError('I am a TypeError') }; var caughtErr; try { funcThatThrows(); } catch(e) { caughtErr = e; } checkError.compatibleConstructor(caughtErr, Error); // true checkError.compatibleConstructor(caughtErr, TypeError); // true checkError.compatibleConstructor(caughtErr, RangeError); // false ``` #### .compatibleMessage(err, errMatcher) ```js var checkError = require('check-error'); var funcThatThrows = function() { throw new TypeError('I am a TypeError') }; var caughtErr; try { funcThatThrows(); } catch(e) { caughtErr = e; } var sameInstance = caughtErr; checkError.compatibleMessage(caughtErr, /TypeError$/); // true checkError.compatibleMessage(caughtErr, 'I am a'); // true checkError.compatibleMessage(caughtErr, /unicorn/); // false checkError.compatibleMessage(caughtErr, 'I do not exist'); // false ``` #### .getConstructorName(errorLike) ```js var checkError = require('check-error'); var funcThatThrows = function() { throw new TypeError('I am a TypeError') }; var caughtErr; try { funcThatThrows(); } catch(e) { caughtErr = e; } var sameInstance = caughtErr; checkError.getConstructorName(caughtErr) // 'TypeError' ``` #### .getMessage(err) ```js var checkError = require('check-error'); var funcThatThrows = function() { throw new TypeError('I am a TypeError') }; var caughtErr; try { funcThatThrows(); } catch(e) { caughtErr = e; } var sameInstance = caughtErr; checkError.getMessage(caughtErr) // 'I am a TypeError' ```