ng-check-markdown

name	ng-check-markdown
description	Complete installation and configuration guide for ngx-markdown and its plugins in Angular projects. Use when setting up markdown rendering with syntax highlighting, diagrams, and advanced features.

ng-check-markdown Skill

Complete step-by-step guide to install and configure ngx-markdown with all optional plugins.

Step 1: Install Core Dependencies

npm install ngx-markdown marked@^17.0.0 --save

Validates: ngx-markdown, marked

Step 2: Install Syntax Highlighting (Prism.js)

2.1 Install Prism.js

npm install prismjs@^1.30.0 --save

2.2 Update angular.json - Add Prism Theme

Add to projects.<project>.architect.build.options.styles:

"styles": [
  "src/styles.scss",
  "node_modules/prismjs/themes/prism-okaidia.min.css"
]

2.3 Update angular.json - Add Prism Core & Languages

Add to projects.<project>.architect.build.options.scripts:

"scripts": [
  "node_modules/prismjs/prism.js",
  "node_modules/prismjs/components/prism-typescript.min.js",
  "node_modules/prismjs/components/prism-javascript.min.js",
  "node_modules/prismjs/components/prism-bash.min.js",
  "node_modules/prismjs/components/prism-csharp.min.js",
  "node_modules/prismjs/components/prism-css.min.js",
  "node_modules/prismjs/components/prism-html.min.js",
  "node_modules/prismjs/components/prism-json.min.js"
]

Step 3: Install Optional Plugin - Line Numbers

3.1 Update angular.json - Add Line Numbers CSS

Add to projects.<project>.architect.build.options.styles:

"node_modules/prismjs/plugins/line-numbers/prism-line-numbers.min.css"

3.2 Update angular.json - Add Line Numbers JS

Add to projects.<project>.architect.build.options.scripts:

"node_modules/prismjs/plugins/line-numbers/prism-line-numbers.js"

3.3 Use in Templates

<markdown lineNumbers [start]="1" [src]="'path/to/file.ts'"></markdown>

Step 4: Install Optional Plugin - Line Highlight

4.1 Update angular.json - Add Line Highlight CSS

Add to projects.<project>.architect.build.options.styles:

"node_modules/prismjs/plugins/line-highlight/prism-line-highlight.min.css"

4.2 Update angular.json - Add Line Highlight JS

Add to projects.<project>.architect.build.options.scripts:

"node_modules/prismjs/plugins/line-highlight/prism-line-highlight.js"

4.3 Use in Templates

<markdown lineHighlight [line]="'1-5, 10'" [src]="'path/to/file.ts'"></markdown>

Step 5: Install Optional Plugin - Command Line

5.1 Update angular.json - Add Command Line CSS

Add to projects.<project>.architect.build.options.styles:

"node_modules/prismjs/plugins/command-line/prism-command-line.min.css"

5.2 Update angular.json - Add Command Line JS

Add to projects.<project>.architect.build.options.scripts:

"node_modules/prismjs/plugins/command-line/prism-command-line.js"

5.3 Use in Templates

<markdown
  commandLine
  [user]="'alice'"
  [host]="'server'"
  [output]="'2, 4-6'"
  [src]="'path/to/file.bash'">
</markdown>

Step 6: Install Mermaid Diagram Support

6.1 Install Mermaid

npm install mermaid@^11.0.0 --save

6.2 Update angular.json - Add Mermaid JS

Add to projects.<project>.architect.build.options.scripts:

"node_modules/mermaid/dist/mermaid.min.js"

6.3 Initialize Mermaid in app.config.ts

import mermaid from 'mermaid';

(window as any).mermaid = mermaid;
mermaid.initialize({
  startOnLoad: false,
  theme: 'dark'
});

6.4 Use in Templates

<markdown mermaid [src]="'path/to/diagram.md'"></markdown>

Step 7: Install Optional Plugin - Copy to Clipboard

7.1 Install Clipboard.js

npm install clipboard@^2.0.11 --save

7.2 Update angular.json - Add Clipboard JS

Add to projects.<project>.architect.build.options.scripts:

"node_modules/clipboard/dist/clipboard.min.js"

7.3 Use in Templates

<markdown clipboard [src]="'path/to/file.ts'"></markdown>

Step 8: Install Optional Plugin - KaTeX Math Rendering

8.1 Install KaTeX

npm install katex@^0.16.0 --save

8.2 Update angular.json - Add KaTeX CSS

Add to projects.<project>.architect.build.options.styles:

"node_modules/katex/dist/katex.min.css"

8.3 Update angular.json - Add KaTeX JS

Add to projects.<project>.architect.build.options.scripts:

"node_modules/katex/dist/katex.min.js",
"node_modules/katex/dist/contrib/auto-render.min.js"

8.4 Use in Templates

<markdown katex [src]="'path/to/file.md'"></markdown>

Step 9: Install Optional Plugin - Emoji Support

9.1 Install Emoji Toolkit

npm install emoji-toolkit@^10.0.0 --save

9.2 Update angular.json - Add Emoji JS

Add to projects.<project>.architect.build.options.scripts:

"node_modules/emoji-toolkit/lib/js/joypixels.min.js"

9.3 Use in Templates

<markdown emoji [data]="'I :heart: ngx-markdown'"></markdown>

Step 10: Configure ngx-markdown Provider (Standalone)

10.1 Update app.config.ts

import { ApplicationConfig } from '@angular/core';
import { provideMarkdown, MERMAID_OPTIONS } from 'ngx-markdown';
import mermaid from 'mermaid';

// Initialize mermaid
(window as any).mermaid = mermaid;
mermaid.initialize({
  startOnLoad: false,
  theme: 'dark'
});

export const appConfig: ApplicationConfig = {
  providers: [
    provideMarkdown({
      mermaidOptions: {
        provide: MERMAID_OPTIONS,
        useValue: {
          darkMode: true,
          theme: 'base',
        },
      },
    }),
  ],
};

Step 11: Use Markdown Component

11.1 Load from Remote File

<markdown [src]="'path/to/file.md'"></markdown>

11.2 Load from Variable

<markdown [data]="markdownContent"></markdown>

11.3 Load Static Content

<markdown ngPreserveWhitespaces>
  # Heading

  ```typescript
  const x = 42;

```

Verification Checklist

After completing all steps:

• npm install completes without errors
• ng build succeeds
• Markdown renders as HTML (not plain text)
• Code blocks display with syntax colors
• Mermaid diagrams render as visual elements
• No console errors or warnings
• All plugin features work as expected

Full angular.json Example

Reference the complete styles and scripts array:

{
  "projects": {
    "my-app": {
      "architect": {
        "build": {
          "options": {
            "styles": [
              "src/styles.scss",
              "node_modules/prismjs/themes/prism-okaidia.min.css",
              "node_modules/prismjs/plugins/line-numbers/prism-line-numbers.min.css",
              "node_modules/prismjs/plugins/line-highlight/prism-line-highlight.min.css",
              "node_modules/prismjs/plugins/command-line/prism-command-line.min.css",
              "node_modules/katex/dist/katex.min.css"
            ],
            "scripts": [
              "node_modules/prismjs/prism.js",
              "node_modules/prismjs/components/prism-typescript.min.js",
              "node_modules/prismjs/components/prism-bash.min.js",
              "node_modules/prismjs/components/prism-csharp.min.js",
              "node_modules/prismjs/plugins/line-numbers/prism-line-numbers.js",
              "node_modules/prismjs/plugins/line-highlight/prism-line-highlight.js",
              "node_modules/prismjs/plugins/command-line/prism-command-line.js",
              "node_modules/mermaid/dist/mermaid.min.js",
              "node_modules/clipboard/dist/clipboard.min.js",
              "node_modules/katex/dist/katex.min.js",
              "node_modules/katex/dist/contrib/auto-render.min.js",
              "node_modules/emoji-toolkit/lib/js/joypixels.min.js"
            ]
          }
        }
      }
    }
  }
}

Minimal Setup (Core Only)

If you only need basic markdown rendering without plugins:

# Install
npm install ngx-markdown marked@^17.0.0 prismjs@^1.30.0 --save

# Update app.config.ts
import { provideMarkdown } from 'ngx-markdown';

export const appConfig: ApplicationConfig = {
  providers: [
    provideMarkdown(),
  ],
};

# Add to angular.json styles
"node_modules/prismjs/themes/prism-okaidia.min.css"

# Add to angular.json scripts
"node_modules/prismjs/prism.js",
"node_modules/prismjs/components/prism-typescript.min.js"

Troubleshooting

Markdown not rendering: Check provideMarkdown() is in app.config.ts
No syntax colors: Verify Prism CSS/JS in angular.json
Mermaid not working: Check mermaid().initialize() is called before app bootstrap
Plugins not working: Ensure CSS/JS files are listed in angular.json in correct order

Audit Checklist — Diagnose Broken Setups

When checking an existing project for markdown/Prism issues, verify all of the following:

1. angular.json scripts must not be empty

# Check
grep -A5 '"scripts"' angular.json

If "scripts": [], Prism JS is not loaded — code blocks will render as plain text with no colours even if the CSS is present.

2. Prism CSS must be in angular.json styles — not injected dynamically

Anti-pattern (broken in production builds and dev server with base-href changes):

// ❌ Never do this
async loadPrismJsTheme() {
  const link = document.createElement('link');
  link.href = 'node_modules/prismjs/themes/prism-okaidia.min.css'; // path not valid after build
  document.head.appendChild(link);
}

Correct approach — CSS in angular.json styles, no runtime injection needed:

"styles": [
  "src/styles.scss",
  "node_modules/prismjs/themes/prism-okaidia.min.css"
]

If a LibraryLoaderService or similar service has a loadPrismJsTheme() / loadPrismJsCss() method, remove it and ensure the CSS is in angular.json. Also remove any calls to it from markdown-renderer.component.ts.

3. Scan pattern — check all demos at once

Get-ChildItem "demos" -Recurse -Filter "angular.json" | ForEach-Object {
  Write-Host "=== $($_.FullName) ==="
  Select-String -Path $_.FullName -Pattern "prism|scripts" | Select-Object -ExpandProperty Line
}

# Find any library-loader with the anti-pattern
Get-ChildItem "demos" -Recurse -Filter "library-loader*" | ForEach-Object {
  $content = Get-Content $_.FullName -Raw
  if ($content -match "loadPrismJsTheme|loadPrismJsCss") {
    Write-Host "❌ Anti-pattern found: $($_.FullName)"
  }
}

# Find any renderers still calling the anti-pattern
Get-ChildItem "demos" -Recurse -Filter "markdown-renderer.component.ts" | ForEach-Object {
  $content = Get-Content $_.FullName -Raw
  if ($content -match "loadPrismJsTheme|loadPrismJsCss") {
    Write-Host "❌ Active call found: $($_.FullName)"
  }
}