[Highlight.js + line number] This snippet adds line number support to Highlight.js. Besides, special css trick is applied to stop the line numbers from being selected and copied. #tags: highlight, lepton

example.js

import HighlightJS from 'highlight.js'

createHighlightedCodeBlock (content, language) {
  let lineNumber = 0
  const highlightedContent = HighlightJS.highlightAuto(content, [language]).value

  /* Highlight.js wraps comment blocks inside <span class="hljs-comment"></span>.
     However, when the multi-line comment block is broken down into diffirent
     table rows, only the first row, which is appended by the <span> tag, is
     highlighted. The following code fixes it by appending <span> to each line
     of the comment block. */
  const commentPattern = /<span class="hljs-comment">(.|\n)*?<\/span>/g
  const adaptedHighlightedContent = highlightedContent.replace(commentPattern, data => {
    return data.replace(/\r?\n/g, () => {
      return '\n<span class="hljs-comment">'
    })
  })

  const contentTable = adaptedHighlightedContent.split(/\r?\n/).map(lineContent => {
    return `<tr>
              <td class='line-number' data-pseudo-content=${++lineNumber}></td>
              <td>${lineContent}</td>
            </tr>`
  }).join('')

  return `<pre><code><table class='code-table'>${contentTable}</table></code></pre>`
}

/*
 * Transform the snippet from plain text to html markup which includes line number
 * support. This method returns an object that can be consumed by a React component.
 * @content   plain text for snippet
 * @language  the language for the snippet
 */
createMarkup (content, language) {
  return { __html: this.createHighlightedCodeBlock(content, language) }
}

// Consumed by React
// <div dangerouslySetInnerHTML={ this.createMarkup(content, language) }/>

style.css

.line-number {
  text-align: right;
  padding-right: 20px;
  display: inline-block;
  color: rgba(0,0,0,0.2);
  width: 40px;
  font-size: 11px;
  font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;
}

/* Technique to disable line numbers from being selected and copied. 
   Checkout this post for more details http://codepen.io/danoc/pen/ByGKZv */
[data-pseudo-content]::before,
[data-pseudo-content--before]::before,
[data-pseudo-content--after]::after {
  content: attr(data-pseudo-content);
}