escape.js

/** Used to map characters to HTML entities. */
const htmlEscapes = {
  "&": "&",
  "<": "&lt;",
  ">": "&gt;",
  '"': "&quot;",
  "'": "&#39;",
};

/** Used to match HTML entities and HTML characters. */
const reUnescapedHtml = /[&<>"']/g;
const reHasUnescapedHtml = RegExp(reUnescapedHtml.source);

/**
 * Converts the characters "&", "<", ">", '"', and "'" in `string` to their
 * corresponding HTML entities.
 *
 * **Note:** No other characters are escaped. To escape additional
 * characters use a third-party library like [_he_](https://mths.be/he).
 *
 * Though the ">" character is escaped for symmetry, characters like
 * ">" and "/" don't need escaping in HTML and have no special meaning
 * unless they're part of a tag or unquoted attribute value. See
 * [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands)
 * (under "semi-related fun fact") for more details.
 *
 * When working with HTML you should always
 * [quote attribute values](http://wonko.com/post/html-escaping) to reduce
 * XSS vectors.
 */
function escape(string) {
  return string && reHasUnescapedHtml.test(string)
    ? string.replace(reUnescapedHtml, (chr) => htmlEscapes[chr])
    : string || "";
}

module.exports = {
  escape,
};