aaac7fed
 liuqimichale
add
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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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