prism-react-renderer

What is prism-react-renderer?

The prism-react-renderer package is a React component that leverages PrismJS, a syntax highlighter written in JavaScript, to render syntax-highlighted code in React applications. It is highly customizable and can be used to implement code highlighting with various themes and styles directly in React projects.

What are prism-react-renderer's main functionalities?

Syntax Highlighting

This feature allows developers to easily implement syntax highlighting in their React applications. The code sample demonstrates how to use prism-react-renderer to highlight JavaScript code with the 'darcula' theme.

import React from 'react';
import { render } from 'react-dom';
import { Prism as SyntaxHighlighter } from 'react-syntax-highlighter';
import { darcula } from 'react-syntax-highlighter/dist/esm/styles/prism';

const Component = () => {
  const codeString = '(num) => num + 1';
  return (
    <SyntaxHighlighter language='javascript' style={darcula}>
      {codeString}
    </SyntaxHighlighter>
  );
};

render(<Component />, document.getElementById('root'));

Custom Theming

This feature demonstrates how to apply a custom theme (in this case, 'nightOwl') to the code highlighting. It shows the flexibility of prism-react-renderer in terms of theming and customization.

import React from 'react';
import Highlight, { defaultProps } from 'prism-react-renderer';
import theme from 'prism-react-renderer/themes/nightOwl';

const exampleCode = `function add(a, b) {
  return a + b;
}`;

const Component = () => (
  <Highlight {...defaultProps} theme={theme} code={exampleCode} language='javascript'>
    {({ className, style, tokens, getLineProps, getTokenProps }) => (
      <pre className={className} style={style}>
        {tokens.map((line, i) => (
          <div {...getLineProps({ line, key: i })}>
            {line.map((token, key) => (
              <span {...getTokenProps({ token, key })} />
            ))}
          </div>
        ))}
      </pre>
    )}
  </Highlight>
);

export default Component;

Other packages similar to prism-react-renderer

react-syntax-highlighter

This package also allows for syntax highlighting in React applications. It supports both PrismJS and Highlight.js and offers a wider range of built-in styles compared to prism-react-renderer. However, prism-react-renderer might be preferred for its simplicity and specific focus on PrismJS.

react-highlight

React-highlight is another syntax highlighting component that uses Highlight.js. It is simpler and less customizable than prism-react-renderer, which might make it suitable for projects that require a more straightforward implementation without the need for extensive customization.

README

prism-react-renderer 🖌️

A lean Prism highlighter component for React
Comes with everything to render Prismjs highlighted code directly to React (Native) elements, global-pollution-free!

Why?

Maybe you need to render some extra UI with your Prismjs-highlighted code, or maybe you'd like to manipulate what Prism renders completely, or maybe you're just using Prism with React and are searching for an easier, global-pollution-free way?

Then you're right where you want to be!

How?

This library tokenises code using Prism and provides a small render-props-driven component to quickly render it out into React. This is why it even works with React Native! It's bundled with a modified version of Prism that won't pollute the global namespace and comes with a couple of common language syntaxes.

(There's also an escape-hatch to use your own Prism setup, just in case)

It also comes with its own VSCode-like theming format, which means by default you can easily drop in different themes, use the ones this library ships with, or create new ones programmatically on the fly.

(If you just want to use your Prism CSS-file themes, that's also no problem)

Table of Contents

• Installation
• Usage
• Basic Props
  • children
  • language
  • code
• Advanced Props
  • theme
  • Prism
• Children Function
  • state
  • prop getters
    • getLineProps
    • getTokenProps
• Theming
• FAQ
• LICENSE

Installation

This module is distributed via npm which is bundled with node and should be installed as one of your project's dependencies:

# npm
npm install --save prism-react-renderer
# yarn
yarn add prism-react-renderer

This package also depends on react. Please make sure you have those installed as well.

Usage

Try it out in the browser

import React from "react";
import { render } from "react-dom";
import Highlight, { defaultProps } from "prism-react-renderer";

const exampleCode = `
(function someDemo() {
  var test = "Hello World!";
  console.log(test);
})();

return () => <App />;
`;

render((
  <Highlight {...defaultProps} code={exampleCode} language="jsx">
    {({ className, style, tokens, getLineProps, getTokenProps }) => (
      <pre className={className} style={style}>
        {tokens.map((line, i) => (
          <div {...getLineProps({ line, key: i })}>
            {line.map((token, key) => (
              <span {...getTokenProps({ token, key })} />
            ))}
          </div>
        ))}
      </pre>
    )}
  </Highlight>,
  document.getElementById('root')
);

<Highlight /> is the only component exposed by this package, as inspired by downshift.

It also exports a defaultProps object which for basic usage can simply be spread onto the <Highlight /> component. It also provides some default theming.

It doesn't render anything itself, it just calls the render function and renders that. "Use a render prop!"! <Highlight>{highlight => <pre>/* your JSX here! */</pre>}</Highlight>

Basic Props

This is the list of props that you should probably know about. There are some advanced props below as well.

Most of these advanced props are included in the defaultProps.

children

function({}) | required

This is called with an object. Read more about the properties of this object in the section "Children Function".

language

string | required

This is the language that your code will be highlighted as. You can see a list of all languages that are supported out of the box here.

code

string | required

This is the code that will be highlighted.

Advanced Props

theme

PrismTheme | required; default is provided in defaultProps export

If a theme is passed, it is used to generate style props which can be retrieved via the prop-getters which are described in "Children Function".

A default theme is provided by the defaultProps object.

Read more about how to theme react-prism-renderer in the section "Theming".

Prism

PrismLib | required; default is provided in defaultProps export

This is the Prismjs library itself. A vendored version of Prism is provided (and also exported) as part of this library. This vendored version doesn't pollute the global namespace, is slimmed down, and doesn't conflict with any installation of prismjs you might have.

If you're only using Prism.highlight you can choose to use prism-react-renderer's exported, vendored version of Prism instead.

But if you choose to use your own Prism setup, simply pass Prism as a prop:

// Whichever way you're retrieving Prism here:
import Prism from 'prismjs/components/prism-core';

<Highlight Prism={Prism} {/* ... */} />

Children Function

This is where you render whatever you want to based on the output of <Highlight />. You use it like so:

const ui = (
  <Highlight>
    {highlight => (
      // use utilities and prop getters here, like highlight.className, highlight.getTokenProps, etc.
      <pre>{/* more jsx here */}</pre>
    )}
  </Highlight>
);

The properties of this highlight object can be split into two categories as indicated below:

state

These properties are the flat output of <Highlight />. They're generally "state" and are what you'd usually expect from a render-props-based API.

property	type	description
tokens	Token[][]	This is a doubly nested array of tokens. The outer array is for separate lines, the inner for tokens, so the actual content.
className	string	This is the class you should apply to your wrapping element, typically a <pre>

A "Token" is an object that represents a piece of content for Prism. It has a types property, which is an array of types that indicate the purpose and styling of a piece of text, and a content property, which is the actual text.

You'd typically iterate over tokens, rendering each line, and iterate over its items, rendering out each token, which is a piece of this line.

prop getters

See Kent C. Dodds' blog post about prop getters

These functions are used to apply props to the elements that you render. This gives you maximum flexibility to render what, when, and wherever you like.

You'd typically call these functions with some dictated input and add on all other props that it should pass through. It'll correctly override and modify the props that it returns to you, so passing props to it instead of adding them directly is advisable.

property	type	description
getLineProps	function({})	returns the props you should apply to any list of tokens, i.e. the element that contains your tokens.
getTokenProps	function({})	returns the props you should apply to the elements displaying tokens that you render.

getLineProps

You need to add a line property (type: Token[]) to the object you're passing to getLineProps; It's also advisable to add a key.

This getter will return you props to spread onto your line elements (typically <div>s).

It will typically return a className (if you pass one it'll be appended), children, style (if you pass one it'll be merged). It also passes on all other props you pass to the input.

The className will always contain .token-line.

getTokenProps

You need to add a token property (type: Token) to the object you're passing to getTokenProps; It's also advisable to add a key.

This getter will return you props to spread onto your token elements (typically <span>s).

It will typically return a className (if you pass one it'll be appended), children, style (if you pass one it'll be merged). It also passes on all other props you pass to the input.

The className will always contain .token. This also provides full compatibility with your old Prism CSS-file themes.

Theming

The defaultProps you'd typically apply in a basic use-case, contain a default theme. This theme is duotoneDark.

While all classNames are provided with <Highlight />, so that you could use your good old Prism CSS-file themes, you can also choose to use react-prism-renderer's themes.

These themes are JSON-based and are heavily inspired by VSCode's theme format.

Their syntax, expressed in Flow looks like the following:

{
  plain: StyleObj,
  styles: Array<{
    types: string[],
    languages?: string[],
    style: StyleObj
  }>
}

The plain property provides a base style-object. This style object is directly used in the style props that you'll receive from the prop getters, if a theme prop has been passed to <Highlight />.

The styles property contains an array of definitions. Each definition contains a style property, that is also just a style object. These styles are limited by the types and languages properties.

The types properties is an array of token types that Prism outputs. The languages property limits styles to highlighted languages.

When converting a Prism CSS theme it's mostly just necessary to use classes as types and convert the declarations to object-style-syntax and put them on style.

FAQ

How do I use my old Prism css themes?

prism-react-renderer still returns you all proper classNames via the prop getters, when you use it. By default however it uses its new theming system, which output a couple of style props as well.

If you don't pass theme to the <Highlight /> component it will default to not outputting any style props, while still returning you the className props, like so:

<Highlight
  {...defaultProps}
  code={exampleCode}
  language="jsx"
  theme={undefined}
>
  {highlight => null /* ... */}
</Highlight>

How do I prevent a theme and the vendored Prism to be bundled?

Since the default theme and the vendored Prism library in prism-react-renderer come from defaultProps, if you wish to pass your own Prism library in, and not use the built-in theming, you simply need to leave it out to allow your bundler to tree-shake those:

import Highlight from "prism-react-renderer";
import Prism from "prismjs"; // Different source

<Highlight Prism={Prism} code={exampleCode} language="jsx">
  {highlight => null /* ... */}
</Highlight>;

You can also import the vendored Prism library on its own:

import { Prism } from "prism-react-renderer";
// or
import Prism from "prism-react-renderer/prism";

LICENSE

MIT