ngx-markdown
ngx-markdown is an Angular library that combines...
Demo available @ https://jfcere.github.io/ngx-markdown
StackBlitz available @ https://stackblitz.com/edit/ngx-markdown
Table of contents
Installation
ngx-markdown
To add ngx-markdown along with the required marked library to your package.json
use the following commands.
npm install ngx-markdown marked@^15.0.0 --save
Syntax highlight
:bell: Syntax highlight is optional, skip this step if you are not planning to use it
To add Prism.js library to your package.json
use the following command.
npm install prismjs@^1.28.0 --save
To activate Prism.js syntax highlight you will need to include...
- prism.js core library -
node_modules/prismjs/prism.js
file - a highlight css theme - from
node_modules/prismjs/themes
directory - desired code language syntax files - from
node_modules/prismjs/components
directory
Additional themes can be found by browsing the web such as Prism-Themes or Mokokai for example.
If you are using Angular CLI you can follow the angular.json
example below...
"styles": [
"styles.css",
+ "node_modules/prismjs/themes/prism-okaidia.css"
],
"scripts": [
+ "node_modules/prismjs/prism.js",
+ "node_modules/prismjs/components/prism-csharp.min.js", # c-sharp language syntax
+ "node_modules/prismjs/components/prism-css.min.js" # css language syntax
]
Line Numbers plugin
To use the line numbers plugin that shows line numbers in code blocks, in addition to Prism.js configuration files, you will need to include the following files from prismjs/plugins/line-numbers
directory to your application:
- CSS styling for line numbers -
prism-line-numbers.css
- line numbers plugin script -
prism-line-numbers.js
If you are using Angular CLI you can follow the angular.json
example below...
"styles": [
"src/styles.css",
"node_modules/prismjs/themes/prism-okaidia.css",
+ "node_modules/prismjs/plugins/line-numbers/prism-line-numbers.css"
],
"scripts": [
"node_modules/prismjs/prism.js",
"node_modules/prismjs/components/prism-csharp.min.js",
"node_modules/prismjs/components/prism-css.min.js",
+ "node_modules/prismjs/plugins/line-numbers/prism-line-numbers.js"
]
Using markdown
component and/or directive, you will be able to use the lineNumbers
property to activate the plugin. The property can be used in combination with either data
for variable binding, src
for remote content or using transclusion for static markdown.
Additionally, you can use start
input property to specify the offset number for the first display line.
<markdown
lineNumbers
[start]="5"
[src]="path/to/file.js">
</markdown>
Line Highlight plugin
To use the line highlight plugin that highlights specific lines and/or line ranges in code blocks, in addition to Prism.js configuration files, you will need to include the following files from prismjs/plugins/line-highlight
directory to your application:
- CSS styling for line highlight -
prism-line-highlight.css
- line highlight plugin script -
prism-line-highlight.js
If you are using Angular CLI you can follow the angular.json
example below...
"styles": [
"src/styles.css",
"node_modules/prismjs/themes/prism-okaidia.css",
+ "node_modules/prismjs/plugins/line-highlight/prism-line-highlight.css"
],
"scripts": [
"node_modules/prismjs/prism.js",
"node_modules/prismjs/components/prism-csharp.min.js",
"node_modules/prismjs/components/prism-css.min.js",
+ "node_modules/prismjs/plugins/line-highlight/prism-line-highlight.js"
]
Using markdown
component and/or directive, you will be able to use the lineHighlight
property to activate the plugin. The property can be used in combination with either data
for variable binding, src
for remote content or using transclusion for static markdown.
Use line
input property to specify the line(s) to highlight and optionally there is a lineOffset
property to specify the starting line of code your snippet represents.
<markdown
lineHighlight
[line]="'6, 10-16'"
[lineOffset]="5"
[src]="path/to/file.js">
</markdown>
Command Line Plugin
To use the command line plugin that displays a command line with a prompt and, optionally, the output/response from the commands, you will need to include the following files from prismjs/plugins/command-line
directory to your application:
- CSS styling for command line -
prism-command-line.css
- command line plugin script -
prism-command-line.js
If you are using Angular CLI you can follow the angular.json
example below...
"styles": [
"src/styles.css",
"node_modules/prismjs/themes/prism-okaidia.css",
+ "node_modules/prismjs/plugins/command-line/prism-command-line.css"
],
"scripts": [
"node_modules/prismjs/prism.js",
"node_modules/prismjs/components/prism-csharp.min.js",
"node_modules/prismjs/components/prism-css.min.js",
+ "node_modules/prismjs/plugins/command-line/prism-command-line.js"
]
Using markdown
component and/or directive, you will be able to use the commandLine
property to activate the plugin. The property can be used in combination with either data
for variable binding, src
for remote content or using transclusion for static markdown.
For a server command line, specify the user and host names using the user
and host
input properties. The resulting prompt displays a #
for the root user and $
for all other users. For any other command line, such as a Windows prompt, you may specify the entire prompt using the prompt
input property.
You may also specify the lines to be presented as output (no prompt and no highlighting) through the output
property in the following simple format:
- A single number refers to the line with that number
- Ranges are denoted by two numbers, separated with a hyphen (-)
- Multiple line numbers or ranges are separated by commas
- Whitespace is allowed anywhere and will be stripped off
<markdown
commandLine
[user]="'chris'"
[host]="'remotehost'"
[output]="'2, 4-8'"
[src]="'path/to/file.bash'">
</markdown>
Optionally, to automatically present some lines as output without providing the line numbers, you can prefix those lines with any string and specify the prefix using the filterOutput
input property. For example, [filterOutput]="'(out)'"
will treat lines beginning with (out)
as output and remove the prefix.
<markdown
commandLine
[prompt]="'PS C:\Users\Chris>'"
[filterOutput]="'(out)'">
```powershell
Get-Date
(out)
(out)Sunday, November 7, 2021 8:19:21 PM
(out)
```
</markdown>
Emoji support
:bell: Emoji support is optional, skip this step if you are not planning to use it
To add Emoji-Toolkit library to your package.json
use the following command.
npm install emoji-toolkit@^9.0.0 --save
To activate Emoji-Toolkit for emoji suppport you will need to include...
- Emoji-Toolkit library -
node_modules/emoji-toolkit/lib/js/joypixels.min.js
If you are using Angular CLI you can follow the angular.json
example below...
"scripts": [
+ "node_modules/emoji-toolkit/lib/js/joypixels.min.js",
]
Emoji plugin
Using markdown
component and/or directive, you will be able to use the emoji
property to activate Emoji-Toolkit plugin that converts emoji shortnames such as :heart:
to native unicode emojis.
<markdown emoji>
I :heart: ngx-markdown
</markdown>
:blue_book: You can refer to this Emoji Cheat Sheet for a complete list of shortnames.
Math rendering
:bell: Math rendering is optional, skip this step if you are not planning to use it
To add KaTeX library to your package.json
use the following command.
npm install katex@^0.16.0 --save
To activate KaTeX math rendering you will need to include...
- KaTex JavaScript library -
node_modules/katex/dist/katex.min.js
file - KaTex Auto-Render extension -
node_modules/katex/dist/contrib/auto-render.min.js,
file - KaTex CSS customization -
node_modules/katex/dist/katex.min.css
file
If you are using Angular CLI you can follow the angular.json
example below...
"styles": [
"styles.css",
+ "node_modules/katex/dist/katex.min.css"
],
"scripts": [
+ "node_modules/katex/dist/katex.min.js",
+ "node_modules/katex/dist/contrib/auto-render.min.js",
]
KaTeX plugin
Using markdown
component and/or directive, you will be able to use the katex
property to activate KaTeX plugin that renders mathematical expression to HTML.
<markdown
katex
[src]="path/to/file.md">
</markdown>
Optionally, you can use katexOptions
property to specify both the KaTeX options and the KaTeX Auto-Render options.
import { KatexOptions } from 'ngx-markdown';
public options: KatexOptions = {
displayMode: true,
throwOnError: false,
errorColor: '#cc0000',
delimiters: [...],
...
};
<markdown
katex
[katexOptions]="options"
[src]="path/to/file.md">
</markdown>
:blue_book: Follow official KaTeX options and KaTeX Auto-Render options documentation for more details on the available options.
Diagrams tool
:bell: Diagram support is optional, skip this step if you are not planning to use it
To add Mermaid library to your package.json
use the following command.
npm install mermaid@^11.0.0 --save
To activate Mermaid diagramming and charting tool you will need to include...
- Mermaid JavaScript library -
node_modules/mermaid/dist/mermaid.min.js
file
If you are using Angular CLI you can follow the angular.json
example below...
"scripts": [
+ "node_modules/mermaid/dist/mermaid.min.js",
]
Mermaid plugin
Using markdown
component and/or directive, you will be able to use the mermaid
property to activate Mermaid plugin that renders Markdown-inspired text definitions to create and modify diagrams dynamically.
<markdown
mermaid
[src]="path/to/file.md">
</markdown>
Global configuration
You can provide a global configuration for mermaid configuration options to use across your application with the mermaidOptions
in the MarkdownModuleConfig
either with provideMarkdown
provide-function for standalone components or MarkdownModule.forRoot()
for module configuration.
Using the provideMarkdown
function
provideMarkdown({
mermaidOptions: {
provide: MERMAID_OPTIONS,
useValue: {
darkMode: true,
look: 'handDrawn',
...
},
},
}),
Using the MarkdownModule
import
MarkdownModule.forRoot({
mermaidOptions: {
provide: MERMAID_OPTIONS,
useValue: {
darkMode: true,
look: 'handDrawn',
...
},
},
}),
Component configuration
Additionally, you can specify mermaid configuration options on component directly using mermaidOptions
property.
import { MermaidAPI } from 'ngx-markdown';
public options: MermaidAPI.MermaidConfig = {
darkMode: true,
look: 'handDrawn',
...
};
<markdown
mermaid
[mermaidOptions]="options"
[src]="'path/to/file.md'">
</markdown>
:blue_book: Follow official Mermaid documentation for more details on diagrams and charts syntax.
Copy-to-clipboard
:bell: Copy-to-clipboard support is optional, skip this step if you are not planning to use it
To add Clipboard library to your package.json
use the following command.
npm install clipboard@^2.0.11 --save
To activate Clipboard allowing copy-to-clipboard you will need to include...
- Clipboard JavaScript library -
node_modules/clipboard/dist/clipboard.min.js
file
If you are using Angular CLI you can follow the angular.json
example below...
"scripts": [
+ "node_modules/clipboard/dist/clipboard.min.js",
]
Clipboard plugin
Using markdown
component and/or directive, you will be able to use the clipboard
property to activate Clipboard plugin that enable copy-to-clipboard for code block from a single click.
<markdown
clipboard
[src]="path/to/file.md">
</markdown>
Default button
The clipboard
plugin provide an unstyled default button with a default behavior out of the box if no alternative is used.
Customize button toolbar
The clipboard button is placed inside a wrapper element that can be customize using the .markdown-clipboard-toolbar
CSS selector in your global styles.css/scss
file.
This allows to override the default positionning of the clipboard button and play with the visibility of the button using the .hover
CSS selector that is applied on the toolbar when the mouse cursor enters and leaves the code block element.
Customize default button
To customize the default button styling, use the .markdown-clipboard-button
CSS selector in your global styles.css/scss
file. You can also customized the "copied" state happening after the button is clicked using the .copied
CSS selector.
Using global configuration
You can provide a custom component to use globaly across your application with the clipboardOptions
in the MarkdownModuleConfig
either with provideMarkdown
provide-function for standalone components or MarkdownModule.forRoot()
for module configuration.
Using the provideMarkdown
function
provideMarkdown({
clipboardOptions: {
provide: CLIPBOARD_OPTIONS,
useValue: {
buttonComponent: ClipboardButtonComponent,
},
},
})
Using the MarkdownModule
import
MarkdownModule.forRoot({
clipboardOptions: {
provide: CLIPBOARD_OPTIONS,
useValue: {
buttonComponent: ClipboardButtonComponent,
},
},
}),
Using a component
You can also provide your custom component using the clipboardButtonComponent
input property when using the clipboard
directive.
import { Component } from '@angular/core';
@Component({
selector: 'app-clipboard-button',
template: `<button (click)="onClick()">Copy</button>`,
})
export class ClipboardButtonComponent {
onClick() {
alert('Copied to clipboard!');
}
}
import { ClipboardButtonComponent } from './clipboard-button-component';
@Component({ ... })
export class ExampleComponent {
readonly clipboardButton = ClipboardButtonComponent;
}
<markdown
clipboard
[clipboardButtonComponent]="clipboardButton">
</markdown>
Using ng-template
Alternatively, the clipboard
directive can be used in conjonction with ng-template
to provide a custom button implementation via the clipboardButtonTemplate
input property on the markdown
component.
<ng-template #buttonTemplate>
<button (click)="onCopyToClipboard()">...</button>
</ng-template>
<markdown
clipboard
[clipboardButtonTemplate]="buttonTemplate">
</markdown>
:blue_book: Refer to the ngx-markdown clipboard plugin demo for live examples.
Configuration
The ngx-markdown library can be used either with the standalone components or with modules configuration. Please follow the configuration section that matches your application.
Standalone components
Use the provideMarkdown
provide-function in your application configuration ApplicationConfig
to be able to provide the MarkdownComponent
and MarkdownPipe
to your standalone components and/or inject the MarkdownService
.
import { NgModule } from '@angular/core';
+ import { provideMarkdown } from 'ngx-markdown';
export const appConfig: ApplicationConfig = {
providers: [
+ provideMarkdown(),
],
};
Modules configuration
You must import MarkdownModule
inside your main application module (usually named AppModule) with forRoot
to be able to use the markdown
component, directive, pipe and/or MarkdownService
.
import { NgModule } from '@angular/core';
+ import { MarkdownModule } from 'ngx-markdown';
import { AppComponent } from './app.component';
@NgModule({
imports: [
+ MarkdownModule.forRoot(),
],
declarations: [AppComponent],
bootstrap: [AppComponent],
})
export class AppModule { }
Use forChild
when importing MarkdownModule
into other application modules to allow you to use the same parser configuration across your application.
import { NgModule } from '@angular/core';
+ import { MarkdownModule } from 'ngx-markdown';
import { HomeComponent } from './home.component';
@NgModule({
imports: [
+ MarkdownModule.forChild(),
],
declarations: [HomeComponent],
})
export class HomeModule { }
Remote file configuration
If you want to use the [src]
attribute to directly load a remote file, in order to keep only one instance of HttpClient
and avoid issues with interceptors, you also have to provide HttpClient
:
Using the provideMarkdown
function
providers: [
+ provideHttpClient(),
+ provideMarkdown({ loader: HttpClient }),
],
Using the MarkdownModule
import
imports: [
+ HttpClientModule,
+ MarkdownModule.forRoot({ loader: HttpClient }),
],
Sanitization
As of ngx-markdown v9.0.0 sanitization is enabled by default and uses Angular DomSanitizer
with SecurityContext.HTML
to avoid XSS vulnerabilities. The SecurityContext
level can be changed using the sanitize
property when configuring MarkdownModule
.
Using the provideMarkdown
function
import { SecurityContext } from '@angular/core';
provideMarkdown()
provideMarkdown({
sanitize: SecurityContext.NONE
})
Using the MarkdownModule
import
import { SecurityContext } from '@angular/core';
MarkdownModule.forRoot()
MarkdownModule.forRoot({
sanitize: SecurityContext.NONE
})
:blue_book: Follow Angular DomSanitizer documentation for more information on sanitization and security contexts.
You can bypass sanitization using the markdown component, directive or pipe using the disableSanitizer
option as follow:
<markdown
[data]="markdown"
[disableSanitizer]="true">
</markdown>
<div markdown
[data]="markdown"
[disableSanitizer]="true">
</div>
<div [innerHTML]="markdown | markdown : { disableSanitizer: true } | async"></div>
MarkedOptions
Optionally, markdown parsing can be configured using MarkedOptions that can be provided with the MARKED_OPTIONS
injection token via the markedOptions
property of the forRoot
method of MarkdownModule
.
Using the provideMarkdown
function
import { MARKED_OPTIONS, provideMarkdown } from 'ngx-markdown';
provideMarkdown(),
provideMarkdown({
markedOptions: {
provide: MARKED_OPTIONS,
useValue: {
gfm: true,
breaks: false,
pedantic: false,
},
},
}),
Using the MarkdownModule
import
import { MarkdownModule, MARKED_OPTIONS } from 'ngx-markdown';
MarkdownModule.forRoot(),
MarkdownModule.forRoot({
loader: HttpClient,
markedOptions: {
provide: MARKED_OPTIONS,
useValue: {
gfm: true,
breaks: false,
pedantic: false,
},
},
}),
MarkedOptions.renderer
MarkedOptions
also exposes the renderer
property which allows you to override token rendering for your whole application.
The example uses a factory function and override the default blockquote token rendering by adding a CSS class for custom styling when using Bootstrap CSS:
import { MARKED_OPTIONS, MarkedOptions, MarkedRenderer } from 'ngx-markdown';
export function markedOptionsFactory(): MarkedOptions {
const renderer = new MarkedRenderer();
renderer.blockquote = (text: string) => {
return '<blockquote class="blockquote"><p>' + text + '</p></blockquote>';
};
return {
renderer: renderer,
gfm: true,
breaks: false,
pedantic: false,
};
}
Using the provideMarkdown
function
provideMarkdown({
markedOptions: {
provide: MARKED_OPTIONS,
useFactory: markedOptionsFactory,
},
}),
Using the MarkdownModule
import
MarkdownModule.forRoot({
markedOptions: {
provide: MARKED_OPTIONS,
useFactory: markedOptionsFactory,
},
}),
Marked extensions
You can provide marked extensions using the markedExtensions
property that accepts an array of extensions when configuring MarkdownModule
.
Using the provideMarkdown
function
import { gfmHeadingId } from 'marked-gfm-heading-id';
providemarkdown({
markedExtensions: [gfmHeadingId()],
}),
Using the MarkdownModule
import
import { gfmHeadingId } from 'marked-gfm-heading-id';
MarkdownModule.forRoot({
markedExtensions: [gfmHeadingId()],
}),
Usage
ngx-markdown
provides different approaches to help you parse markdown to your application depending on your needs.
:bulb: As of Angular 6, the template compiler strips whitespace by default. Use ngPreserveWhitespaces
directive to preserve whitespaces such as newlines in order for the markdown-formatted content to render as intended.
https://angular.io/api/core/Component#preserveWhitespaces
Component
You can use markdown
component to either parse static markdown directly from your HTML markup, load the content from a remote URL using src
property or bind a variable to your component using data
property. You can get a hook on load complete using load
output event property, on loading error using error
output event property or when parsing is completed using ready
output event property.
<markdown ngPreserveWhitespaces>
# Markdown
</markdown>
<markdown
[src]="'path/to/file.md'"
(load)="onLoad($event)"
(error)="onError($event)">
</markdown>
<markdown
[data]="markdown"
(ready)="onReady()">
</markdown>
<markdown
[data]="markdown"
[inline]="true">
</markdown>
Directive
The same way the component works, you can use markdown
directive to accomplish the same thing.
<div markdown ngPreserveWhitespaces>
# Markdown
</div>
<div markdown
[src]="'path/to/file.md'"
(load)="onLoad($event)"
(error)="onError($event)">
</div>
<div markdown
[data]="markdown"
(ready)="onReady()">
</div>
<div markdown
[data]="markdown"
[inline]="true">
</div>
Pipe
Using markdown
pipe to transform markdown to HTML allow you to chain pipe transformations and will update the DOM when value changes. It is important to note that, because the marked
parsing method returns a Promise
, it requires the use of the async
pipe.
<div [innerHTML]="typescriptMarkdown | language : 'typescript' | markdown | async"></div>
The markdown
pipe allow you to use all the same plugins as the component by providing the options parameters.
<div [innerHTML]="typescriptMarkdown | language : 'typescript' | markdown : { emoji: true, inline: true } | async"></div>
This is the MarkdownPipeOptions
parameters interface, those options are the same as the ones available for the markdown
component:
export interface MarkdownPipeOptions {
decodeHtml?: boolean;
inline?: boolean;
emoji?: boolean;
katex?: boolean;
katexOptions?: KatexOptions;
mermaid?: boolean;
mermaidOptions?: MermaidAPI.MermaidConfig;
markedOptions?: MarkedOptions;
disableSanitizer?: boolean;
}
Service
You can use MarkdownService
to have access to markdown parsing, rendering and syntax highlight methods.
import { Component, OnInit } from '@angular/core';
import { MarkdownService } from 'ngx-markdown';
@Component({ ... })
export class ExampleComponent implements OnInit {
constructor(private markdownService: MarkdownService) { }
ngOnInit() {
console.log(this.markdownService.parse('I am using __markdown__.'));
}
}
Renderer
Tokens can be rendered in a custom manner by either...
- providing the
renderer
property with the MarkedOptions
when importing MarkdownModule.forRoot()
into your main application module (see Configuration section) - using
MarkdownService
exposed renderer
Here is an example of overriding the default heading token rendering through MarkdownService
by adding an embedded anchor tag like on GitHub:
import { Component, OnInit } from '@angular/core';
import { MarkdownService } from 'ngx-markdown';
@Component({
selector: 'app-example',
template: '<markdown># Heading</markdown>',
})
export class ExampleComponent implements OnInit {
constructor(private markdownService: MarkdownService) { }
ngOnInit() {
this.markdownService.renderer.heading = (text: string, level: number) => {
const escapedText = text.toLowerCase().replace(/[^\w]+/g, '-');
return '<h' + level + '>' +
'<a name="' + escapedText + '" class="anchor" href="#' + escapedText + '">' +
'<span class="header-link"></span>' +
'</a>' + text +
'</h' + level + '>';
};
}
}
This code will output the following HTML:
<h1>
<a name="heading" class="anchor" href="#heading">
<span class="header-link"></span>
</a>
Heading
</h1>
:blue_book: Follow official marked.renderer documentation for the list of tokens that can be overriden.
Re-render Markdown
In some situations, you might need to re-render markdown after making changes. If you've updated the text this would be done automatically, however if the changes are internal to the library such as rendering options, you will need to inform the MarkdownService
that it needs to update.
To do so, inject the MarkdownService
and call the reload()
function as shown below.
import { MarkdownService } from 'ngx-markdown';
constructor(
private markdownService: MarkdownService,
) { }
update() {
this.markdownService.reload();
}
:blue_book: Refer to the ngx-markdown re-render demo for a live example.
Syntax highlight
When using static markdown you are responsible to provide the code block with related language.
<markdown ngPreserveWhitespaces>
+ ```typescript
const myProp: string = 'value';
+ ```
</markdown>
When using remote URL ngx-markdown will use the file extension to automatically resolve the code language.
<markdown [src]="'path/to/file.html'"></markdown>
<markdown [src]="'path/to/file.php'"></markdown>
When using variable binding you can optionally use language
pipe to specify the language of the variable content (default value is markdown when pipe is not used).
<markdown [data]="markdown | language : 'typescript'"></markdown>
Demo application
A demo is available @ https://jfcere.github.io/ngx-markdown and its source code can be found inside the demo
directory.
The following commands will clone the repository, install npm dependencies and serve the application @ http://localhost:4200
git clone https://github.com/jfcere/ngx-markdown.git
npm install
npm start
AoT compilation
Building with AoT is part of the CI and is tested every time a commit occurs so you don't have to worry at all.
Road map
Here is the list of tasks that will be done on this library in the near future ...
- Add a FAQ section to the README.md
- Improve flexibily for some options
Contribution
Contributions are always welcome, just make sure that ...
- Your code style matches with the rest of the project
- Unit tests pass
- Linter passes
Support Development
The use of this library is totally free and no donation is required.
As the owner and primary maintainer of this project, I am putting a lot of time and effort beside my job, my family and my private time to bring the best support I can by answering questions, addressing issues and improving the library to provide more and more features over time.
If this project has been useful, that it helped you or your business to save precious time, don't hesitate to give it a star and to consider a donation to support its maintenance and future development.
License
Licensed under MIT.