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@leafygreen-ui/code

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@leafygreen-ui/code

leafyGreen UI Kit Code Blocks

19.0.0

latest

Source

npm

Version published: last week

Maintainers: 6

Created: 6 years ago

Source

Code

npm (scoped)

View on MongoDB.design

Installation

Yarn

yarn add @leafygreen-ui/code

NPM

npm install @leafygreen-ui/code

Source Code Pro Font

In addition to using a limited amount of our standard brand font, this component uses the open-source monospace font "Source Code Pro". For this component to display correctly, loading the following weights / styles of "Source Code Pro" is necessary:

400 / normal
400 / italic
600 / normal

You can find instructions for using Google's CDN for font delivery, and download "Source Code Pro" on Google Fonts.

We recommend using Google's CDN for loading this font to optimize for caching the assets, speeding up loading times for webpages as a result. We use the following HTML in our <head> tags to load the necessary variants of "Source Code Pro":

<link rel="preconnect" href="https://fonts.gstatic.com" />
<link href="https://fonts.googleapis.com/css2?family=Source+Code+Pro:ital,wght@0,400;0,600;1,400&display=swap" rel="stylesheet" />

Example

import Code from '@leafygreen-ui/code';

const codeSnippet = `
function greeting(entity) {
  return \`Hello, \${entity}!\`;
}

console.log(greeting('World'));
`;

const SomeComponentWithPanel = () => (
  <Code
    language="javascript"
    showLineNumbers={true}
    onCopy={() => {}}
    darkMode={true}
    panel={
      <Panel
        onChange={() => {}}
        languageOptions={[]}
        showCustomActionButtons
        customActionButtons={[]}
        title="Title"
      />
    }
  >
    {codeSnippet}
  </Code>
);

const SomeComponentWithoutPanel = () => (
  <Code
    language="javascript"
    showLineNumbers={true}
    onCopy={() => {}}
    darkMode={true}
    copyButtonAppearance="persist"
  >
    {codeSnippet}
  </Code>
);

Props

Code

Prop	Type	Description	Default
`children` (Required)	`string`	This is the code snippet that will be rendered in the code block.	`''`
`language` (Required)	`'javascript'`, `'typescript'`, `'cs'`, `'csharp'`, `'cpp'`, `'go'`, `'http'`,`'java'`, `'perl'`, `'php'`, `'python'`, `'ruby'`, `'scala'`, `'swift'`, `'kotlin'`,`'objectivec'`, `'dart'`, `'bash'`, `'shell'`, `'sql'`, `'yaml'`, `'json'`, `'diff'`, `'xml'`, `'none'`	The language to highlight the code block as. When set to `'none'`, no syntax highlighting will be applied.
`darkMode`	`boolean`	Determines whether or not the component will appear in dark mode.	`false`
`className`	`string`	Applies a className to the root element's classList.
`showLineNumbers`	`boolean`	Shows line numbers next to each line of code in the passed code snippet. NOTE: While you can set this to `true` regardless of the code component being multiline, the line numbers will not be displayed if the `multiline` prop is `true`.	`false`
`lineNumberStart`	`number`	Specifies the number by which to start line numbering.	`1`
`onCopy`	`Function`	Callback fired when Code is copied
`expandable`	`boolean`	When true, allows the code block to be expanded and collapsed when there are more than 5 lines of code.	`false`
`highlightLines`	`Array<number` \| `[number, number]>`	An optional array of lines to highlight. The array can only contain numbers corresponding to the line numbers to highlight, and / or tuples representing a range (e.g. `[6, 10]`);
`copyButtonAppearance`	`'none'`, `'hover'`, `'persist'`	Determines the appearance of the copy button without a panel. The copy button allows the code block to be copied to the user's clipboard by clicking the button. If `hover`, the copy button will only appear when the user hovers over the code block. On mobile devices, the copy button will always be visible. If `persist`, the copy button will always be visible. If `none`, the copy button will not be rendered. *Note: `panel` cannot be used with `copyButtonAppearance`. Either use `copyButtonAppearance` or `panel`, not both*.	`hover`
`panel`	`React.ReactNode`	Slot to pass the `<Panel/>` sub-component which will render the top panel with a language switcher, custom action buttons, and copy button. If no props are passed to the panel sub-component, the panel will render with only the copy button. *Note: `copyButtonAppearance` cannot be used with `panel`. Either use `copyButtonAppearance` or `panel`, not both.*	``
`isLoading`	`boolean`	Determines whether or not the loading skeleton will be rendered in place of the code block. If`true`, the language switcher and copy button will be disabled in the top panel.	`false`
`baseFontSize`	`'13'` \| `'16'`	Determines the base font-size of the component	`13`
`customKeywords`	`{ [key: string]: string }`	Custom keywords to be highlighted in the code block. The key is the keyword to be highlighted, and the value is the classname to be applied to the keyword. E.g. `customKeywords: {{ 'keyword': 'className' }}`	`{}`

Panel

Prop	Type	Description	Default
`showCustomActionButtons`	`boolean`	Shows custom action buttons in the panel if set to `true` and there is at least one item in `customActionButtons`.	`false`
`customActionButtons`	`Array<React.ReactElement>`	An array of custom action buttons using the `IconButton` component. For example: `[<IconButton><Icon glyph="Cloud" /></IconButton>, <IconButton><Icon glyph="Code" /></IconButton>]`	`[]`
`title`	`string`	Shows a filename-like title in the window chrome frame.	`''`
`languageOptions`	`Array<LanguageOption>`	An array of language options. When provided, a LanguageSwitcher dropdown is rendered.
`onChange`	`(language: LanguageOption) => void`	A change handler triggered when the language is changed. Invalid when no `languageOptions` are provided.

interface LanguageOption {
  displayName: string;
  language: Language;
  image?: React.ReactElement;
}

Test Harnesses

getTestUtils()

getTestUtils() is a util that allows consumers to reliably interact with LG Code in a product test suite. If the Code component cannot be found, an error will be thrown.

Usage

import { getTestUtils } from '@leafygreen-ui/code';

const utils = getTestUtils(lgId?: `lg-${string}`); // lgId refers to the custom `data-lgid` attribute passed to `Code`. It defaults to 'lg-code' if left empty.

Single `Code` component

import { render } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import Code, { getTestUtils } from '@leafygreen-ui/code';

...

test('code', () => {
  render(
    <Code
      language="javascript"
      panel={
        <Panel
          onChange={() => {}}
          languageOptions={languageOptions}
          title="Title"
        />
      }
    >
      {codeSnippet}
    </Code>
  );

  const { getLanguage, getLanguageSwitcherUtils, getIsLoading, getCopyButtonUtils, getExpandButtonUtils } = getTestUtils();
  const { getInput, getOptions, getOptionByValue, getInputValue, isDisabled: isLanguageSwitcherDisabled } = getLanguageSwitcherUtils();
  const { getButton, queryButton, findButton, isDisabled } = getCopyButtonUtils();
  const { getButton, queryButton, findButton } = getExpandButtonUtils();

  expect(getLanguage()).toBe('javascript');
  expect(getTitle()).toBe('Title');
  expect(getInput()).toBeInTheDocument();
  expect(getOptions()).toHaveLength(2);
  expect(getOptionByValue('js')).toBeInTheDocument();
  expect(getInputValue()).toBe('javascript');
  expect(isLanguageSwitcherDisabled()).toBe(false);
  expect(getIsLoading()).toBe(false);
  expect(getCopyButtonUtils().getButton()).toBeInTheDocument();
  expect(getCopyButtonUtils().findButton()).toBeInTheDocument();
  expect(getCopyButtonUtils().queryButton()).toBeInTheDocument();
  expect(getCopyButtonUtils().isDisabled()).toBe(false);
  expect(getExpandButtonUtils().getButton()).toBeInTheDocument();
  expect(getExpandButtonUtils().findButton()).toBeInTheDocument();
  expect(getExpandButtonUtils().queryButton()).toBeInTheDocument();
  expect(isExpanded()).toBe(false);
});

Multiple `Code` components

When testing multiple Code components, it is recommended to add the custom data-lgid attribute to each Code.

import { render } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import { Code, getTestUtils } from '@leafygreen-ui/code';

...

test('code', () => {
  render(
    <>
      <Code
        language="javascript"
        panel={<Panel/>}
        data-lgid="lg-code-1"
      >
      {codeSnippet}
      </Code>
      <Code
        language="python"
        panel={<Panel/>}
        data-lgid="lg-code-2"
      >
        {codeSnippet}
      </Code>
    </>
  );

  const testUtils1 = getTestUtils('lg-code-1');
  const testUtils2 = getTestUtils('lg-code-2');

  // First Code
  expect(testUtils1.getLanguage()).toBe('javascript');

  // Second Code
  expect(testUtils2.getLanguage()).toBe('python');
});

Test Utils

const {
  getLanguage,
  getIsLoading,
  getTitle,
  queryPanel,
  getLanguageSwitcherUtils: {
    getInput,
    getOptions,
    getOptionByValue,
    isDisabled,
  },
  getCopyButtonUtils: { getButton, queryButton, findButton, isDisabled },
  getExpandButtonUtils: { getButton, queryButton, findButton },
} = getTestUtils();

Util	Description	Returns
`getLanguage()`	Returns the current language of the code block	`string`
`getLanguageSwitcherUtils()`	Returns utils for interacting with the language switcher	`LanguageSwitcherUtils`
`getIsLoading()`	Returns whether the code block is in loading state	`boolean`
`getCopyButtonUtils()`	Returns utils for interacting with the copy button	Button test utils return type
`getExpandButtonUtils()`	Returns utils for interacting with the expand button	Button test utils return type
`getIsExpanded()`	Returns whether the code block is expanded	`boolean`
`getTitle()`	Returns the title of the code block	`string` \| `null`
`queryPanel()`	Returns the panel element	`HTMLElement` \| `null`

LanguageSwitcherUtils

Util	Description	Returns
`getInput()`	Returns the language switcher trigger	`HTMLButtonElement`
`getInputValue()`	Returns the language switcher input value	`string`
`getOptions()`	Returns all options in the language switcher	`Array<HTMLElement>`
`getOptionByValue(value: string)`	Returns the option element by its value	`HTMLElement` \| `null`
`isDisabled()`	Returns whether the language switcher is disabled	`boolean`

FAQs

What is @leafygreen-ui/code?

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Package last updated on 29 May 2025

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Install

@leafygreen-ui/code

Code

Installation

Yarn

NPM

Source Code Pro Font

Example

Props

Code

Panel

Test Harnesses

getTestUtils()

Usage

Single Code component

Multiple Code components

Test Utils

LanguageSwitcherUtils

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Single `Code` component

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