Map definition with chaining

gistfile1.js

var Map = (function Map(method) {
	if (typeof method === "function") {
		Map.prototype[method.name] = method;
		return Map;
	}
	if (!(this instanceof Map)) {
		return new Map();
	}
	this.data = {};
})(function has(key) {
	return Object.prototype.hasOwnProperty.call(this.data, key);
})(function get(key) {
	if (this.has(key)) {
		return this.data[key];
	}
})(function put(key, value) {
	var oldValue = this.get(key);
	this.data[key] = value;
	return oldValue;
})(function remove(key) {
	var oldValue = this.get(key);
	delete this.data[key];
	return oldValue;
})(function keys() {
	return Object.keys(this.data).sort();
})(function values() {
	return this.keys().map(this.get.bind(this));
})(function size() {
	return this.keys().length;
});