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kitabcitab/node_modules/es-abstract/2015/StringGetIndexProperty.js

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+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+var callBound = require('call-bind/callBound');
+
+var $TypeError = GetIntrinsic('%TypeError%');
+
+var $charAt = callBound('String.prototype.charAt');
+
+var isString = require('is-string');
+var isNegativeZero = require('is-negative-zero');
+var unbox = require('unbox-primitive');
+
+var CanonicalNumericIndexString = require('./CanonicalNumericIndexString');
+var IsInteger = require('./IsInteger');
+var IsPropertyKey = require('./IsPropertyKey');
+var Type = require('./Type');
+
+// https://262.ecma-international.org/6.0/#sec-stringgetindexproperty
+
+module.exports = function StringGetIndexProperty(S, P) {
+	if (typeof S === 'string' || !isString(S)) {
+		throw new $TypeError('Assertion failed: `S` must be a boxed String Object');
+	}
+	if (!IsPropertyKey(P)) {
+		throw new $TypeError('Assertion failed: `P` must be a Property Key');
+	}
+
+	if (Type(P) !== 'String') {
+		return void undefined;
+	}
+
+	var index = CanonicalNumericIndexString(P);
+	if (typeof index === 'undefined' || !IsInteger(index) || isNegativeZero(index)) {
+		return void undefined;
+	}
+
+	var str = unbox(S);
+	var len = str.length;
+	if (index < 0 || len <= index) {
+		return void undefined;
+	}
+
+	var resultStr = $charAt(str, index);
+
+	return {
+		'[[Configurable]]': false,
+		'[[Enumerable]]': true,
+		'[[Value]]': resultStr,
+		'[[Writable]]': false
+	};
+};