Angular Highlight.js
Instant code highlighting, auto-detect language, super easy to use
Table of Contents
Installation
Install with NPM
npm i ngx-highlightjsUsage
Provide the config for HIGHLIGHT_OPTIONS in main.ts file
import { HIGHLIGHT_OPTIONS } from 'ngx-highlightjs';
bootstrapApplication(AppComponent, {
providers: [
{
provide: HIGHLIGHT_OPTIONS,
useValue: {
fullLibraryLoader: () => import('highlight.js')
}
}
]
})Note: This will add highlight.js library including all languages to your bundle.
To avoid import everything from highlight.js library, you should import each language you want to highlight manually.
Import only the core library and the needed highlighting languages
import { HIGHLIGHT_OPTIONS } from 'ngx-highlightjs';
bootstrapApplication(AppComponent, {
providers: [
{
provide: HIGHLIGHT_OPTIONS,
useValue: {
coreLibraryLoader: () => import('highlight.js/lib/core'),
lineNumbersLoader: () => import('ngx-highlightjs/line-numbers'), // Optional, only if you want the line numbers
languages: {
typescript: () => import('highlight.js/lib/languages/typescript'),
css: () => import('highlight.js/lib/languages/css'),
xml: () => import('highlight.js/lib/languages/xml')
},
themePath: 'path-to-theme.css' // Optional, and useful if you want to change the theme dynamically
}
}
]
})HighlightOptions API
| Name | Description |
|---|---|
| fullLibraryLoader | A function that returns a promise that loads highlight.js full script |
| coreLibraryLoader | A function that returns a promise that loads highlight.js core script |
| lineNumbersLoader | A function that returns a promise that loads line-numbers script which adds line numbers to the highlight code |
| languages | The set of languages to register |
| config | Set highlight.js config, see configure-options |
| themePath | The path to highlighting theme CSS file |
NOTE: Since the update of [email protected], should use
coreLibraryLoader: () => import('highlight.js/lib/core')instead ofcoreLibraryLoader: () => import('highlight.js/lib/highlight')
Import highlighting theme
In version >=6.1.0, A new way is available to load the theme dynamically! this is OPTIONAL, you can still use the traditional way.
Dynamic way
Set the theme path in the global config, this makes it possible to change the theme on the fly, which is useful if you have light and dark theme in your app.
providers: [
{
provide: HIGHLIGHT_OPTIONS,
useValue: {
// ...
themePath: 'assets/styles/solarized-dark.css'
}
}
]If you want to import it from the app dist folder, then copy the themes you want to your assets directory, or you can
just use a CDN link to the theme.
When switching between the app themes you need to call the setTheme(path) from the HighlightLoader service.
import { HighlightLoader } from 'ngx-highlightjs';
export class AppComponent {
constructor(private hljsLoader: HighlightLoader) {
}
// Assume you have a callback function when your app theme is changed
onAppThemeChange(appTheme: 'dark' | 'light') {
this.hljsLoader.setTheme(appTheme === 'dark' ? 'assets/styles/solarized-dark.css' : 'assets/styles/solarized-light.css');
}
}You can still use the traditional way
Traditional way
To import highlight.js theme from the node_modules directory in angular.json
"styles": [
"styles.css",
"../node_modules/highlight.js/styles/github.css",
]
Or directly in src/style.scss
@import '~highlight.js/styles/github.css';List of all available themes from highlight.js
Use highlight directive
The following line will highlight the given code and append it to the host element
import { HighlightModule } from 'ngx-highlightjs';
@Component({
selector: 'app-root',
template: `
<pre><code [highlight]="code"></code></pre>
`,
standalone: true,
imports: [
HighlightModule
]
})
export class AppComponent {
}Options
| Name | Type | Description |
|---|---|---|
| [highlight] | string | Accept code string to highlight, default null |
| [languages] | string[] | An array of language names and aliases restricting auto detection to only these languages, default: null |
| [lineNumbers] | boolean | A flag that indicates adding line numbers to highlighted code element |
| (highlighted) | HighlightAutoResult | Stream that emits the result object when element is highlighted |
NOTE
In Angular 10, when building your project, you might get a
warning WARNING in ... CommonJS or AMD dependencies can cause optimization bailouts.
To avoid this warning, add the following in your angular.json
{
"projects": {
"project-name": {
"architect": {
"build": {
"options": {
"allowedCommonJsDependencies": [
"highlight.js"
]
}
}
}
}
}
}Read more about CommonJS dependencies configuration
Plus package
This package contains the following features:
- Highlight gists using gists API
- Highlight code directly from URL
Usage
The plus package relies on HttpClient to make the http requests, ensure that it is imported in your main.ts file
import { provideHttpClient } from '@angular/common/http';
bootstrapApplication(AppComponent, {
providers: [
provideHttpClient(),
{
provide: HIGHLIGHT_OPTIONS,
useValue: // ...
}
]
})Highlight a gist file
- Use
[gist]directive with the gist id to get the response through the output(gistLoaded). - Once
(gistLoaded)emits, you will get access to the gist response. - Use
gistContentpipe to extract the file content from gist response using gist file name.
Example:
import { HighlightPlusModule } from 'ngx-highlightjs';
@Component({
selector: 'app-root',
template: `
<pre [gist]="gistId" (gistLoaded)="gist = $event">
<code [highlight]="gist | gistContent: 'main.js'"></code>
</pre>
`,
standalone: true,
imports: [HighlightPlusModule]
})
export class AppComponent {
}Highlight all gist files
To loop over gist?.files, use keyvalue pipe to pass file name into gistContent pipe.
Example:
import { HighlightPlusModule } from 'ngx-highlightjs';
@Component({
selector: 'app-root',
template: `
<ng-container [gist]="gistId" (gistLoaded)="gist = $event">
<pre *ngFor="let file of gist?.files | keyvalue">
<code [highlight]="gist | gistContent: file.key"></code>
</pre>
</ng-container>
`,
standalone: true,
imports: [HighlightPlusModule, CommonModule]
})
export class AppComponent {
}Highlight code from URL directly
Use the pipe codeFromUrl with the async pipe together to get the code text from a raw URL.
Example:
import { HighlightPlusModule } from 'ngx-highlightjs';
@Component({
selector: 'app-root',
template: `
<pre>
<code [highlight]="codeUrl | codeFromUrl | async"></code>
</pre>
`,
standalone: true,
imports: [HighlightPlusModule, CommonModule]
})
export class AppComponent {
}Providing Gist API secret (Optional)
To take full advantage of the gist loader feature, the package provides GIST_OPTIONS token to set your clientId
and clientSecret with the gist http requests, you can provide it in main.ts like in this example:
import { GIST_OPTIONS } from 'ngx-highlightjs/plus'
bootstrapApplication(AppComponent, {
providers: [
provideHttpClient(),
{
provide: HIGHLIGHT_OPTIONS,
useValue: // ...
},
{
provide: GIST_OPTIONS,
useValue: {
clientId: 'CLIENT_ID',
clientSecret: 'CLIENT_SECRET'
}
},
]
})Development
This project uses Angular CLI to build the package.
$ ng build ngx-highlightjsIssues
If you identify any errors in the library, or have an idea for an improvement, please open an issue.
Author
Murhaf Sousli