var toInteger = require('./_to-integer'); var defined = require('./_defined'); // true -> String#at // false -> String#codePointAt module.exports = function (TO_STRING) { return function (that, pos) { var s = String(defined(that)); var i = toInteger(pos); var l = s.length; var a, b; if (i < 0 || i >= l) return TO_STRING ? '' : undefined; a = s.charCodeAt(i); return a < 0xd800 || a > 0xdbff || i + 1 === l || (b = s.charCodeAt(i + 1)) < 0xdc00 || b > 0xdfff ? TO_STRING ? s.charAt(i) : a : TO_STRING ? s.slice(i, i + 2) : (a - 0xd800 << 10) + (b - 0xdc00) + 0x10000; }; };