1 import { Injectable } from '@angular/core'
3 import * as MarkdownIt from 'markdown-it'
6 export class MarkdownService {
15 static ENHANCED_RULES = MarkdownService.TEXT_RULES.concat([ 'image' ])
17 private textMarkdownIt: MarkdownIt.MarkdownIt
18 private enhancedMarkdownIt: MarkdownIt.MarkdownIt
21 this.textMarkdownIt = this.createMarkdownIt(MarkdownService.TEXT_RULES)
22 this.enhancedMarkdownIt = this.createMarkdownIt(MarkdownService.ENHANCED_RULES)
25 textMarkdownToHTML (markdown: string) {
26 const html = this.textMarkdownIt.render(markdown)
28 return this.avoidTruncatedLinks(html)
31 enhancedMarkdownToHTML (markdown: string) {
32 const html = this.enhancedMarkdownIt.render(markdown)
34 return this.avoidTruncatedLinks(html)
37 private createMarkdownIt (rules: string[]) {
38 const markdownIt = new MarkdownIt('zero', { linkify: true, breaks: true })
40 for (let rule of rules) {
41 markdownIt.enable(rule)
44 this.setTargetToLinks(markdownIt)
49 private setTargetToLinks (markdownIt: MarkdownIt.MarkdownIt) {
50 // Snippet from markdown-it documentation: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md#renderer
51 const defaultRender = markdownIt.renderer.rules.link_open || function (tokens, idx, options, env, self) {
52 return self.renderToken(tokens, idx, options)
55 markdownIt.renderer.rules.link_open = function (tokens, index, options, env, self) {
56 const token = tokens[index]
58 const targetIndex = token.attrIndex('target')
59 if (targetIndex < 0) token.attrPush([ 'target', '_blank' ])
60 else token.attrs[targetIndex][1] = '_blank'
62 const relIndex = token.attrIndex('rel')
63 if (relIndex < 0) token.attrPush([ 'rel', 'noopener noreferrer' ])
64 else token.attrs[relIndex][1] = 'noopener noreferrer'
66 // pass token to default renderer.
67 return defaultRender(tokens, index, options, env, self)
71 private avoidTruncatedLinks (html) {
72 return html.replace(/<a[^>]+>([^<]+)<\/a>\s*...(<\/p>)?$/mi, '$1...')