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- // 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)), length = str.length, first, second;
- pos = toInteger(pos);
- // Account for out-of-bounds indices:
- if (pos < 0 || pos >= length) return undefined;
- // Get the first code unit
- first = str.charCodeAt(pos);
- if (first >= 0xd800 && first <= 0xdbff && length > 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;
- };
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