You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
27 lines
818 B
27 lines
818 B
2 years ago
|
// 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;
|
||
|
|
};
|