| // Based on: https://github.com/mathiasbynens/String.prototype.codePointAt |
| // Thanks @mathiasbynens ! |
| |
| 'use strict'; |
| |
| var toInteger = require('../../../number/to-integer') |
| , validValue = require('../../../object/valid-value'); |
| |
| module.exports = function (pos) { |
| var str = String(validValue(this)), l = str.length, first, second; |
| pos = toInteger(pos); |
| |
| // Account for out-of-bounds indices: |
| if (pos < 0 || pos >= l) return undefined; |
| |
| // Get the first code unit |
| first = str.charCodeAt(pos); |
| if ((first >= 0xD800) && (first <= 0xDBFF) && (l > pos + 1)) { |
| second = str.charCodeAt(pos + 1); |
| if (second >= 0xDC00 && second <= 0xDFFF) { |
| // http://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae |
| return (first - 0xD800) * 0x400 + second - 0xDC00 + 0x10000; |
| } |
| } |
| return first; |
| }; |
