pretty-print-json

Pretty-print JSON data into HTML to indent and colorize

Source is written in functional TypeScript, and pretty-print-json.min.js (minified) is 2.1 KB.

A) Try It Out

Interactive online tool to format JSON:
https://pretty-print-json.js.org

B) Setup

1. Web browser

Load from the jsdelivr.com CDN:

<link rel=stylesheet href=https://cdn.jsdelivr.net/npm/pretty-print-json@3.0/dist/css/pretty-print-json.css>
...
<script src=https://cdn.jsdelivr.net/npm/pretty-print-json@3.0/dist/pretty-print-json.min.js></script>

The minified JS file is 2 KB.

For dark mode, replace pretty-print-json.css with pretty-print-json.dark-mode.css in the <link> tag.

Or to automatically sense dark mode based on the prefers-color-scheme CSS media feature, use pretty-print-json.prefers.css instead.

2. Node.js server

Install package for node:

$ npm install pretty-print-json

Import into your application:

import { prettyPrintJson } from 'pretty-print-json';

C) Usage

1. API

const html = prettyPrintJson.toHtml(data, options?);

2. Example

HTML:

<pre id=account class=json-container></pre>

JavaScript:

Pass data into prettyPrintJson.toHtml(data, options) and display the results.

const data = {
   active: true,
   mode:   '🚃',
   codes:  [48348, 28923, 39080],
   city:   'London',
   };
const elem = document.getElementById('account');
elem.innerHTML = prettyPrintJson.toHtml(data);

3. Options

Name (key)	Type	Default	Description
indent	integer	3	Number of spaces for indentation.
lineNumbers	boolean	false	Wrap HTML in an <ol> tag to support line numbers.*
linkUrls	boolean	true	Create anchor tags for URLs.
linksNewTab	boolean	true	Add a target=_blank attribute setting to anchor tags.
quoteKeys	boolean	false	Always double quote key names.
trailingCommas	boolean	true	Append a comma after the last item in arrays and objects.

*When setting lineNumbers to true, do not use the <pre> tag as the white-space: pre; styling is applied to each line (<li>).

D) TypeScript Declarations

See the TypeScript declarations at the top of the pretty-print-json.ts file.

Customize the output of the function prettyPrintJson.toHtml(data: unknown, options?: FormatOptions) using the options parameter.

The options parameter is a FormatOptions object:

type FormatOptions = {
   indent?:         number,   //number of spaces for indentation
   lineNumbers?:    boolean,  //wrap HTML in an <ol> tag to support line numbers
   linkUrls?:       boolean,  //create anchor tags for URLs
   linksNewTab?:    boolean,  //add a target=_blank attribute setting to anchor tags
   quoteKeys?:      boolean,  //always double quote key names
   trailingCommas?: boolean,  //append a comma after the last item in arrays and objects
   };

Example TypeScript usage with explicit types:

import { prettyPrintJson, FormatOptions } from 'pretty-print-json';

const data = {
   active: true,
   mode:   '🚃',
   codes:  [48348, 28923, 39080],
   city:   'London',
   };
const options: FormatOptions = { linkUrls: true };
const html: string = prettyPrintJson.toHtml(data, options);

E) Build Environment

Check out the runScriptsConfig section in package.json for an interesting approach to organizing build tasks.

CLI Build Tools for package.json

• 🎋 add-dist-header:  Prepend a one-line banner comment (with license notice) to distribution files
• 📄 copy-file-util:  Copy or rename a file with optional package version number
• 📂 copy-folder-util:  Recursively copy files from one folder to another folder
• 🪺 recursive-exec:  Run a command on each file in a folder and its subfolders
• 🔍 replacer-util:  Find and replace strings or template outputs in text files
• 🔢 rev-web-assets:  Revision web asset filenames with cache busting content hash fingerprints
• 🚆 run-scripts-util:  Organize npm package.json scripts into groups of easy to manage commands
• 🚦 w3c-html-validator:  Check the markup validity of HTML files using the W3C validator

---

To see some example HTML results, run npm install, npm test, and then node spec/examples.js.

Feel free to submit questions at:
github.com/center-key/pretty-print-json/issues

MIT License | Blog post