Angular Highlight.js
Instant code highlighting, auto-detect language, super easy to use
Table of Contents
Installation
Install with NPM
npm i ngx-highlightjs
Usage
Import HighlightModule
in your app
import { HighlightModule, HIGHLIGHT_OPTIONS } from 'ngx-highlightjs';
@NgModule({
imports: [
HighlightModule
],
providers: [
{
provide: HIGHLIGHT_OPTIONS,
useValue: {
fullLibraryLoader: () => import('highlight.js/lib/highlight'),
}
}
],
})
export class AppModule { }
Note: By default this will lazy-load highlight.js bundle library including all languages.
To avoid import everything from highlight.js library, you should import each language you want to highlight manually.
Import highlighting languages
To do so, use the injection token HIGHLIGHT_OPTIONS
to provide options:
import { HighlightModule, HIGHLIGHT_OPTIONS } from 'ngx-highlightjs';
@NgModule({
imports: [
HighlightModule
],
providers: [
{
provide: HIGHLIGHT_OPTIONS,
useValue: {
coreLibraryLoader: () => import('highlight.js/lib/highlight'),
lineNumbersLoader: () => import('highlightjs-line-numbers.js'),
languages: {
typescript: () => import('highlight.js/lib/languages/typescript'),
css: () => import('highlight.js/lib/languages/css'),
xml: () => import('highlight.js/lib/languages/xml')}
}
}
],
})
export class AppModule { }
Import highlighting theme
Import highlight.js theme from the node_modules directory in angular.json
"styles": [
"styles.css",
"../node_modules/highlight.js/styles/github.css",
]
Or import it 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
<pre><code [highlight]="code"></code></pre>
Demo stackblitz
Options
-
[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): Stream that emits HighlightResult
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": {
"allowedCommonJsDependencies": [
"highlight.js"
]
}
}
}
}
}
Plus package
In version >= 4, a new sub-package were added with the following features:
- Highlight gists using gists API
- Highlight code directly from URL
Usage
import { HighlightPlusModule } from 'ngx-highlightjs/plus';
@NgModule({
imports: [
HighlightPlusModule
]
})
export class AppModule {
}
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
gistContent
pipe to extract the file content from gist response using gist file name.
Example:
<pre [gist]="gistId" (gistLoaded)="gist = $event">
<code [highlight]="gist | gistContent: 'main.js'"></code>
</pre>
Highlight all gist files
To loop over gist?.files
, use keyvalue
pipe to pass file name into gistContent
pipe.
Example:
<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>
Highlight code from URL directly
Use the pipe codeFromUrl
with the async
pipe together to get the code text from a raw URL.
Example:
<pre>
<code [highlight]="codeUrl | codeFromUrl | async"></code>
</pre>
Development
This project uses Angular CLI to build the package.
$ ng build ngx-highlightjs
Issues
If you identify any errors in the library, or have an idea for an improvement, please open an issue.
Author
Murhaf Sousli
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