voca/reverse_grapheme.js

The ultimate JavaScript string library

'use strict';

require('./internal/is_nil.js');
require('./is_string.js');
var coerce_to_string = require('./internal/coerce_to_string.js');
var _const = require('./internal/const.js');

/**
 * Reverses the `subject` taking care of
 * <a href="https://rainsoft.io/what-every-javascript-developer-should-know-about-unicode/#24surrogatepairs">surrogate pairs</a> and
 * <a href="https://rainsoft.io/what-every-javascript-developer-should-know-about-unicode/#25combiningmarks">combining marks</a>.
 *
 * @function reverseGrapheme
 * @static
 * @since 1.0.0
 * @memberOf Manipulate
 * @param {string} [subject=''] The string to reverse.
 * @return {string} Returns the reversed string.
 * @example
 * v.reverseGrapheme('summer');
 * // => 'remmus'
 *
 * v.reverseGrapheme('𝌆 bar mañana mañana');
 * // => 'anañam anañam rab 𝌆'
 */

function reverseGrapheme(subject) {
  var subjectString = coerce_to_string.coerceToString(subject);
  /**
   * @see https://github.com/mathiasbynens/esrever
   */

  subjectString = subjectString.replace(_const.REGEXP_COMBINING_MARKS, function ($0, $1, $2) {
    return reverseGrapheme($2) + $1;
  }).replace(_const.REGEXP_SURROGATE_PAIRS, '$2$1');
  var reversedString = '';
  var index = subjectString.length;

  while (index--) {
    reversedString += subjectString.charAt(index);
  }

  return reversedString;
}

module.exports = reverseGrapheme;