terriajs/lib/Core/markdownToHtml.js

Geospatial data visualization platform.

'use strict';

/*global require*/
var defined = require('terriajs-cesium/Source/Core/defined');
var MarkdownIt = require('markdown-it');
var DOMPurify = require('dompurify/dist/purify');

var md = new MarkdownIt({
    html: true,
    linkify: true
});

var htmlRegex = /^\s*<[^>]+>/;

/**
 * Convert a String in markdown format (which includes html) into html format.
 * @param  {String} markdownString String in markdown format.
 * @param  {Boolean} allowUnsafeHtml Pass true to allow unsafe html. Defaults to false.
 * @param  {Object} [options] Options to pass to DOMPurify, eg. {ADD_TAGS: ['ying', 'yang']} (https://github.com/cure53/DOMPurify).
 * @return {String} HTML-formatted string.
 */
function markdownToHtml(markdownString, allowUnsafeHtml, options) {
    if (!defined(markdownString) || markdownString.length === 0) {
        return markdownString;
    }
    // If the text looks like html, don't try to interpret it as Markdown because
    // we'll probably break it in the process.
    // It would wrap non-standard tags such as <collapsible>hi</collapsible> in a <p></p>, which is bad.
    var unsafeHtml;
    if (htmlRegex.test(markdownString)) {
        unsafeHtml = markdownString;
    } else {
        // MarkdownIt can't handle something that is not a string primitve.  It can't even handle
        // something that is a string object (instanceof String) rather a string primitive
        // (typeof string === 'string').  So if this isn't a string primitive, call toString
        // on it in order to make it one.
        if (markdownString && typeof markdownString !== 'string') {
            markdownString = markdownString.toString();
        }

        unsafeHtml = md.render(markdownString);
    }
    if (allowUnsafeHtml) {
        return unsafeHtml;
    } else {
        return DOMPurify.sanitize(unsafeHtml, options);
    }
}

module.exports = markdownToHtml;