HORIZON PROJECT

/*!

 * escape-html

 * Copyright(c) 2012-2013 TJ Holowaychuk

 * Copyright(c) 2015 Andreas Lubbe

 * Copyright(c) 2015 Tiancheng "Timothy" Gu

 * MIT Licensed

 */

'use strict';

/**

 * Module variables.

 * @private

 */

var matchHtmlRegExp = /["'&<>]/;

/**

 * Module exports.

 * @public

 */

module.exports = escapeHtml;

/**

 * Escape special characters in the given string of html.

 *

 * @param  {string} string The string to escape for inserting into HTML

 * @return {string}

 * @public

 */

function escapeHtml(string) {

  var str = '' + string;

  var match = matchHtmlRegExp.exec(str);

  if (!match) {

    return str;

  }

  var escape;

  var html = '';

  var index = 0;

  var lastIndex = 0;

  for (index = match.index; index < str.length; index++) {

    switch (str.charCodeAt(index)) {

      case 34: // "

        escape = '"';

        break;

      case 38: // &

        escape = '&';

        break;

      case 39: // '

        escape = ''';

        break;

      case 60: // <

        escape = '<';

        break;

      case 62: // >

        escape = '>';

        break;

      default:

        continue;

    }

    if (lastIndex !== index) {

      html += str.substring(lastIndex, index);

    }

    lastIndex = index + 1;

    html += escape;

  }

  return lastIndex !== index

    ? html + str.substring(lastIndex, index)

    : html;

}