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- 'use strict';
- var $TypeError = require('es-errors/type');
- var callBound = require('call-bind/callBound');
- var $charCodeAt = callBound('String.prototype.charCodeAt');
- var $numberToString = callBound('Number.prototype.toString');
- var $toLowerCase = callBound('String.prototype.toLowerCase');
- var $strSlice = callBound('String.prototype.slice');
- // https://262.ecma-international.org/9.0/#sec-unicodeescape
- module.exports = function UnicodeEscape(C) {
- if (typeof C !== 'string' || C.length !== 1) {
- throw new $TypeError('Assertion failed: `C` must be a single code unit');
- }
- var n = $charCodeAt(C, 0);
- if (n > 0xFFFF) {
- throw new $TypeError('`Assertion failed: numeric value of `C` must be <= 0xFFFF');
- }
- return '\\u' + $strSlice('0000' + $toLowerCase($numberToString(n, 16)), -4);
- };
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