An ES5 Class Creator

es5class.js

// 281 bytes:

/** Return a class with prototype values conditionally inheriting from a super class
* @param {string} name name of the class
* @param {Object<string,any>} prototype prototype values of the class
* @param {Function} [Super] super class inherited by the class
* @return {Function}
*/
function _class(name, prototype, Super) {
	var Class = Function('_', 'return function ' + name + '(){return _(this,arguments)}')(
		function (c,a) {
			return this.apply(c,a) || c;
		}.bind(
			Object.hasOwnProperty.call(prototype, 'constructor') ? prototype.constructor : function() {
				if (Super) {
					Super.call(this, arguments);
				}
			}
		)
	);
	
	Class.prototype = Object.create(
		(Super ? (Class.__proto__ = Super) : Class).prototype,
		{
			constructor: {
				configurable: true,
				value: Class,
				writable: true
			}
		}
	);

	Object.keys(prototype).forEach(function (name) {
		if (name !== 'constructor') {
			Object.defineProperty(Class.prototype, name, {
				configurable: true,
				value: prototype[name],
				writable: true
			});
		}
	});

	return Class;
}

es5class.usage.js

Sup = _class('Sup', {
	constructor () {
		console.log('new Sup()', arguments.length)
	},
	supness() {
		return 'supness'
	}
});

Sub = _class('Sub', {
	constructor () {
		console.log('new Sub()', arguments.length);
		this.constructor.__proto__.apply(this, arguments);
	},
	subness() {
		return 'subness'
	}
}, Sup);

sub = new Sub(5, 2, 9)