es-string-html-methods/helpers/polyfill.js

An ES-spec-compliant shim/polyfill/replacement for the Annex B String.prototype HTML methods that works as far down as ES3

'use strict';

var Call = require('es-abstract/2024/Call');

var callBound = require('call-bound');

var $match = callBound('String.prototype.match');
var $toLowerCase = callBound('String.prototype.toLowerCase');

var safeConcat = require('safe-array-concat');

module.exports = function polyfillHelper(property, implementation) {
	return function polyfill() {
		var method = String.prototype[property];
		if (typeof method !== 'function') {
			return implementation;
		}
		var output = Call(method, '', [' " ']);
		var quotesCount = safeConcat($match(output, /"/g)).length;
		if (output !== $toLowerCase(output) || quotesCount > 2) {
			return implementation;
		}
		try {
			// node <= 0.10 does not throw on a nullish receiver
			Call(method, null);
			Call(method, undefined);
			return implementation;
		} catch (e) { /**/ }

		return method;
	};
};