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2 years ago
'use strict';
var GetIntrinsic = require('get-intrinsic');
var $TypeError = GetIntrinsic('%TypeError%');
var $fromCharCode = GetIntrinsic('%String.fromCharCode%');
var floor = require('./floor');
var modulo = require('./modulo');
var isCodePoint = require('../helpers/isCodePoint');
// https://ecma-international.org/ecma-262/12.0/#sec-utf16encoding
module.exports = function UTF16EncodeCodePoint(cp) {
if (!isCodePoint(cp)) {
throw new $TypeError('Assertion failed: `cp` must be >= 0 and <= 0x10FFFF');
}
if (cp <= 65535) {
return $fromCharCode(cp);
}
var cu1 = $fromCharCode(floor((cp - 65536) / 1024) + 0xD800);
var cu2 = $fromCharCode(modulo(cp - 65536, 1024) + 0xDC00);
return cu1 + cu2;
};