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