Wat!

wat.js

function print(value) {
	if (typeof(value) == 'string')
		return WScript.stdout.write(value);
	if (typeof(value) == 'number') {
		if (isNaN(value))
			return WScript.stdout.write('NaN');
		return WScript.stdout.write(value);
	}
	if (value == null)
		return print("null");
	if (value instanceof Array) {
		return String(value);
	}
	
	WScript.Echo(value);
};

function output(value) {
	if (value instanceof Array) {
		WScript.Echo('Array with ' + value.length + ' elements');
		print(value);
	}
	WScript.Echo(typeof(value));
	print(value);
	WScript.Echo('');
}

var line = null;
while (line != '') {
	WScript.stdout.write(">");
	line = WScript.stdin.readline();
	if (line != '') {
		try {
			var x = eval(line);
			output(x);
		} catch (e) {
			WScript.Echo('Error: ' + e.message);
		}
	}
}