video-extension.js

(function (extension) {
  'use strict';

  if (typeof showdown !== 'undefined') {
    // global (browser or nodejs global)
    extension(showdown);
  } else if (typeof define === 'function' && define.amd) {
    // AMD
    define(['showdown'], extension);
  } else if (typeof exports === 'object') {
    // Node, CommonJS-like
    module.exports = extension(require('showdown'));
  } else {
    // showdown was not found so we throw
    throw Error('Could not find showdown library');
  }

}(function (showdown) {
  'use strict';

  /**
   * 支持 ![](https://video.mp4) 语法的视频显示。
   * 
   * Support for the syntax of video display, syntax: ![](https://video.mp4)
   */
  showdown.extension('video', function () {
    return [

      {
        type:    'output',
        regex:   '<p><img src="(.+(mp4|ogg|webm).*?)"(.+?)\\/>',
        replace: function (match, url, format, other) {
          // Check if we matched the leading \ and return nothing changed if so
          if (url === ('.' + format)) {
            return match;
          } else {
            // src="https://image.png" alt="image alt text" title="image title" width="100" height="auto"
            // var regex = /([a-z]+)="(.*?)"/g;

            // return `<video src="${url}" ${other} controls>I am sorry; your browser does not support HTML5 video in WebM with VP8/VP9 or MP4 with H.264.</video>`;
            return `<video ${other} controls><source src="${url}" type="video/${format}">I am sorry, Your browser does not support the <code>video</code> element.</video>`;
          }
        }
      },
    ];
  });

}));