Fetch Response Parser

Lightweight library to properly handle JSON and other responses from the Fetch API.

Overview

Handling Fetch API responses can be tedious. To get it right one must:

• Check the response's status
• Check the response's content-type
• Call the proper body retrieval method
• Write promise handlers

And most code doesn't even do it!

Instead of writing (or not writing) this boilerplate over and over you can use the Fetch Response Parser.

Installation

npm install fetch-response-parser

Or

yarn add fetch-response-parser

If you want to load from a script tag:

<script src="https://cdn.jsdelivr.net/npm/fetch-response-parser@VERSION/dist/fetch-response-parser.min.js"></script>

Where VERSION is the version number you want to use.

The package contains a minified, moduleless, JavaScript version at fetch-response-parser/dist/fetch-response-parser.min.js

Usage

Handling a JSON response:

const parser = require('fetch-response-parser');

fetch('https://httpbin.org/json').
  then(parser.json()).
  then(json => console.log(json.slideshow.author)).
  catch(error => console.error(error)); // error is an instance of Error

If you're using the module-less version you'd use window.FetchResponseParser instead of parser.

Handling a text response, i.e., returning it as a string:

fetch('https://httpbin.org/html').
  then(parser.text()).
  then(text => console.log(text)).
  catch(error => console.error(error)); // error is an instance of Error

Options

The json function accepts the following options:

• strict - if true raise an error if the response is successful but the body is not JSON; defaults to true

Error Handling

When an error occurs an instance of Error is thrown. This instance has the following additional properties:

• json - Boolean indicating if the error response was JSON
• responseBody - The response body of the error. Can be an Object, if json is true or a String if the response was not JSON
• response - The Fetch API Response
• redirected - Boolean indicating if the response was an HTTP redirect
• redirectedTo - String location of the redirect

Here's an example:

const parser = require('fetch-response-parser');

function handleErorr(error) {
  if(error.json)
    console.error(error.responseBody.some.property);
  else if(error.redirected)
    console.error(`Redirected to: ${error.redirectedTo}`);
  else if(error.responseBody)
    console.error(error.responseBody);
  else
    console.error(error.message);
}

fetch('https://httpbin.org/html').
  then(parser.json()).
  then(json => console.log(json.some.property)).
  catch(handleError);

Author

Skye Shaw (skye.shaw -AT- gmail)

License

Released under the MIT License: http://www.opensource.org/licenses/MIT