var escapeHtmlChar = require('./_escapeHtmlChar'),
      toString = require('./toString');
  
  /** Used to match HTML entities and HTML characters. */
  var reUnescapedHtml = /[&<>"']/g,
      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.
   *
   * @static
   * @since 0.1.0
   * @memberOf _
   * @category String
   * @param {string} [string=''] The string to escape.
   * @returns {string} Returns the escaped string.
   * @example
   *
   * _.escape('fred, barney, & pebbles');
   * // => 'fred, barney, &amp; pebbles'
   */
  function escape(string) {
    string = toString(string);
    return (string && reHasUnescapedHtml.test(string))
      ? string.replace(reUnescapedHtml, escapeHtmlChar)
      : string;
  }
  
  module.exports = escape;