svelte-highlight
Advanced tools
Readme
Syntax highlighting for Svelte using highlight.js.
Try it in StackBlitz.
The Changelog is available on GitHub.
# Yarn
yarn add -D svelte-highlight
# npm
npm i -D svelte-highlight
# pnpm
pnpm i -D svelte-highlight highlight.js
Note that pnpm users must also install highlight.js.
The Highlight component requires two props:
code: text to highlightlanguage: language grammar used to highlight the textImport languages from svelte-highlight/languages.
See SUPPORTED_LANGUAGES.md for a list of supported languages.
<script>
import Highlight from "svelte-highlight";
import typescript from "svelte-highlight/languages/typescript";
const code = "const add = (a: number, b: number) => a + b;";
</script>
<Highlight language={typescript} {code} />
Import styles from svelte-highlight/styles. See SUPPORTED_STYLES.md for a list of supported styles.
There are two ways to apply highlight.js styles.
This component exports highlight.js themes in JavaScript. Import the theme from svelte-highlight/styles and inject it using the svelte:head API.
<script>
import Highlight from "svelte-highlight";
import typescript from "svelte-highlight/languages/typescript";
import github from "svelte-highlight/styles/github";
const code = "const add = (a: number, b: number) => a + b;";
</script>
<svelte:head>
{@html github}
</svelte:head>
<Highlight language={typescript} {code} />
Depending on your set-up, importing a CSS StyleSheet in Svelte may require a CSS file loader. SvelteKit/Vite automatically supports this. For Webpack, refer to examples/webpack.
<script>
import { Highlight } from "svelte-highlight";
import typescript from "svelte-highlight/languages/typescript";
import "svelte-highlight/styles/github.css";
const code = "const add = (a: number, b: number) => a + b;";
</script>
<Highlight language={typescript} {code} />
CSS StyleSheets can also be externally linked from a Content Delivery Network (CDN) like unpkg.com.
Warning Using a CDN is best suited for prototyping and not recommended for production use.
HTML
<!doctype html>
<html lang="en">
<head>
<link
rel="stylesheet"
href="https://unpkg.com/svelte-highlight/styles/github.css"
/>
</head>
</html>
svelte:head
<svelte:head>
<link
rel="stylesheet"
href="https://unpkg.com/svelte-highlight/styles/github.css"
/>
</svelte:head>
Use the HighlightSvelte component for Svelte syntax highlighting.
<script>
import { HighlightSvelte } from "svelte-highlight";
import github from "svelte-highlight/styles/github";
const code = `<button on:click={() => { console.log(0); }}>Increment {count}</button>`;
</script>
<svelte:head>
{@html github}
</svelte:head>
<HighlightSvelte {code} />
The HighlightAuto component uses highlightAuto API.
Warning Auto-highlighting will result in a larger bundle size. Specify a language if possible.
<script>
import { HighlightAuto } from "svelte-highlight";
import github from "svelte-highlight/styles/github";
const code = `body {\n padding: 0;\n color: red;\n}`;
</script>
<svelte:head>
{@html github}
</svelte:head>
<HighlightAuto {code} />
Use the LineNumbers component to render the highlighted code with line numbers.
<script>
import Highlight, { LineNumbers } from "svelte-highlight";
import typescript from "svelte-highlight/languages/typescript";
import atomOneDark from "svelte-highlight/styles/atom-one-dark";
const code = "const add = (a: number, b: number) => a + b";
</script>
<svelte:head>
{@html atomOneDark}
</svelte:head>
<Highlight language={typescript} {code} let:highlighted>
<LineNumbers {highlighted} />
</Highlight>
Set hideBorder to true to hide the border of the line numbers column.
<Highlight language={typescript} {code} let:highlighted>
<LineNumbers {highlighted} hideBorder />
</Highlight>
By default, overflowing horizontal content is contained by a scrollbar.
Set wrapLines to true to hide the border of the line numbers column.
<Highlight language={typescript} {code} let:highlighted>
<LineNumbers {highlighted} wrapLines />
</Highlight>
The line number starts at 1. Customize this via the startingLineNumber prop.
<Highlight language={typescript} {code} let:highlighted>
<LineNumbers {highlighted} startingLineNumber={42} />
</Highlight>
Specify the lines to highlight using the highlightedLines prop. Indices start at zero.
Use --highlighted-background to customize the background color of highlighted lines.
<Highlight language={typescript} {code} let:highlighted>
<LineNumbers
{highlighted}
highlightedLines={[0, 2, 3, 14]}
--highlighted-background="#000"
/>
</Highlight>
Use --style-props to customize styles.
| Style prop | Description | Default value |
|---|---|---|
| --line-number-color | Text color of the line numbers | currentColor |
| --border-color | Border color of the column of line numbers | currentColor |
| --padding-left | Left padding for td elements | 1em |
| --padding-right | Right padding for td elements | 1em |
| --highlighted-background | Background color of highlighted lines | rgba(254, 241, 96, 0.2) |
<Highlight language={typescript} {code} let:highlighted>
<LineNumbers
{highlighted}
--line-number-color="pink"
--border-color="rgba(255, 255, 255, 0.2)"
--padding-left={0}
--padding-right="3em"
--highlighted-background="#000"
/>
</Highlight>
All Highlight components apply a data-language attribute on the codeblock containing the language name.
See SUPPORTED_LANGUAGES.md for a list of supported languages.
[data-language="css"] {
/* custom style rules */
}
Set langtag to true to display the language name in the top right corner of the code block.
Customize the language tag background, color, and border-radius using style props.
See the Languages page for a list of supported languages.
| Style prop | Description | Default value |
|---|---|---|
| --langtag-top | Top position of the langtag | 0 |
| --langtag-right | Right position of the langtag | 0 |
| --langtag-background | Background color of the langtag | inherit |
| --langtag-color | Text color of the langtag | inherit |
| --langtag-border-radius | Border radius of the langtag | 0 |
| --langtag-padding | Padding of the langtag | 1em |
<script>
import { HighlightAuto } from "svelte-highlight";
$: code = `.body { padding: 0; margin: 0; }`;
</script>
<HighlightAuto {code} langtag />
<HighlightAuto
{code}
langtag
--langtag-background="linear-gradient(135deg, #2996cf, 80%, white)"
--langtag-color="#fff"
--langtag-border-radius="6px"
--langtag-padding="0.5rem"
/>
For custom language highlighting, pass a name and register function to the language prop.
Refer to the highlight.js language definition guide for guidance.
<script>
import { Highlight } from "svelte-highlight";
import hljs from "highlight.js";
const language = {
name: "custom-language",
register: (hljs) => {
return {
/** custom language rules */
contains: [],
};
},
};
</script>
<Highlight {language} code="..." />
You can use the await import syntax for code-splitting.
In the example below, the HighlightAuto component and injected styles are dynamically loaded.
<script>
import { onMount } from "svelte";
let component;
let styles;
onMount(async () => {
component = (await import("svelte-highlight")).HighlightAuto;
styles = (await import("svelte-highlight/styles/github")).default;
});
</script>
<svelte:head>
{#if styles}
{@html styles}
{/if}
</svelte:head>
<svelte:component
this={component}
langtag
code={`body {\n padding: 0;\n color: red;\n}`}
/>
Highlight| Name | Type | Default value |
|---|---|---|
| code | any | N/A (required) |
| language | { name: string; register: hljs => object } | N/A (required) |
| langtag | boolean | false |
$$restProps are forwarded to the top-level pre element.
code is highlighted<Highlight
language={typescript}
{code}
on:highlight={(e) => {
/**
* The highlighted HTML as a string.
* @example "<span>...</span>"
*/
console.log(e.detail.highlighted);
}}
/>
LineNumbers| Name | Type | Default value |
|---|---|---|
| highlighted | string | N/A (required) |
| hideBorder | boolean | false |
| wrapLines | boolean | false |
| startingLineNumber | number | 1 |
| highlightedLines | number[] | [] |
$$restProps are forwarded to the top-level div element.
HighlightSvelte| Name | Type | Default value |
|---|---|---|
| code | any | N/A (required) |
| langtag | boolean | false |
$$restProps are forwarded to the top-level pre element.
code is highlighted<HighlightSvelte
{code}
on:highlight={(e) => {
/**
* The highlighted HTML as a string.
* @example "<span>...</span>"
*/
console.log(e.detail.highlighted);
}}
/>
HighlightAuto| Name | Type | Default value |
|---|---|---|
| code | any | N/A (required) |
| langtag | boolean | false |
$$restProps are forwarded to the top-level pre element.
code is highlighted<HighlightAuto
{code}
on:highlight={(e) => {
/**
* The highlighted HTML as a string.
* @example "<span>...</span>"
*/
console.log(e.detail.highlighted);
/**
* The inferred language name
* @example "css"
*/
console.log(e.detail.language);
}}
/>
FAQs
Svelte component library for highlighting code using highlight.js
The npm package svelte-highlight receives a total of 22,079 weekly downloads. As such, svelte-highlight popularity was classified as popular.
We found that svelte-highlight demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
Socket CEO Feross Aboukhadijeh joins a16z partners to discuss how modern, sophisticated supply chain attacks require AI-driven defenses and explore the challenges and solutions in leveraging AI for threat detection early in the development life cycle.
Security News
NIST's new AI Risk Management Framework aims to enhance the security and reliability of generative AI systems and address the unique challenges of malicious AI exploits.
Security News
This episode of the Risky Biz podcast discusses how the rise of small open source packages and the shift towards individual maintainers makes the ecosystem more vulnerable to supply chain attacks.