1 /* eslint-disable babel/new-cap, xo/throw-new-error */
3 module.exports = function (str, pos) {
4 if (str === null || str === undefined) {
10 var size = str.length;
11 var i = pos ? Number(pos) : 0;
13 if (Number.isNaN(i)) {
17 if (i < 0 || i >= size) {
21 var first = str.charCodeAt(i);
23 if (first >= 0xD800 && first <= 0xDBFF && size > i + 1) {
24 var second = str.charCodeAt(i + 1);
26 if (second >= 0xDC00 && second <= 0xDFFF) {
27 return ((first - 0xD800) * 0x400) + second - 0xDC00 + 0x10000;