is-implemented.js

'use strict';

module.exports = function () {
	var map, iterator, result;
	if (typeof Map !== 'function') return false;
	try {
		// WebKit doesn't support arguments and crashes
		map = new Map([['raz', 'one'], ['dwa', 'two'], ['trzy', 'three']]);
	} catch (e) {
		return false;
	}
	if (String(map) !== '[object Map]') return false;
	if (map.size !== 3) return false;
	if (typeof map.clear !== 'function') return false;
	if (typeof map.delete !== 'function') return false;
	if (typeof map.entries !== 'function') return false;
	if (typeof map.forEach !== 'function') return false;
	if (typeof map.get !== 'function') return false;
	if (typeof map.has !== 'function') return false;
	if (typeof map.keys !== 'function') return false;
	if (typeof map.set !== 'function') return false;
	if (typeof map.values !== 'function') return false;

	iterator = map.entries();
	result = iterator.next();
	if (result.done !== false) return false;
	if (!result.value) return false;
	if (result.value[0] !== 'raz') return false;
	if (result.value[1] !== 'one') return false;

	return true;
};