/* eslint-disable babel/new-cap, xo/throw-new-error */
  'use strict';
  module.exports = function (str, pos) {
  	if (str === null || str === undefined) {
  		throw TypeError();
  	}
  
  	str = String(str);
  
  	var size = str.length;
  	var i = pos ? Number(pos) : 0;
  
  	if (Number.isNaN(i)) {
  		i = 0;
  	}
  
  	if (i < 0 || i >= size) {
  		return undefined;
  	}
  
  	var first = str.charCodeAt(i);
  
  	if (first >= 0xD800 && first <= 0xDBFF && size > i + 1) {
  		var second = str.charCodeAt(i + 1);
  
  		if (second >= 0xDC00 && second <= 0xDFFF) {
  			return ((first - 0xD800) * 0x400) + second - 0xDC00 + 0x10000;
  		}
  	}
  
  	return first;
  };