js quiz

quiz.js

/*
 * Author: Jan Kassens
 *
 * Guess the results and run it in Firebug
 * If you got all right with the first try you're a JS Samurai (Ninja is overused)
 */

var tasks = {

	'try/finally': function(){
		var value = 'foo';
		var fn = function(change){
			try {
				return value;
			} finally {
				if (change){
					value = 'bar';
					return 'zomg';
				}
			}
		};
		console.log(fn());
		console.log(fn(true));
		console.log(fn());
	},

	numbers: function(){
		console.log(060 + 070 + 080 + 090);
		var x = '4', y = '4';
		x += 0;
		y *= 1;
		console.log(x + y);
	},

	scope: function(){
		var scope = 'outer';
		(function(){
			if (true) var scope = 'inner';
			console.log(scope);
		})();

		scope = 'outer';
		(function(){
			if (false) var scope = 'inner';
			console.log(scope);
		})();

		scope = 'outer';
		(function(){
			if (!scope) var scope = 'inner';
			console.log(scope);
		})();
	},

	'truthy?': function(){
		(function(thing){
			console.log(">%s< is ", thing.toString(), thing ? 'truthy' : 'falsy');
			return arguments.callee;
		})
		(0)
		(1)
		('0')
		('1')
		(Number(0))
		(new Number(0))
		(new Number(0) + new Number(0))
		('')
		(String(''))
		(new String(''))
		(new String('') + new String(''))
		([])
		({});
	},

	prototypes: function(){
		try {
			var result = Array.prototype.join.call("input", " ");
			console.log(result);
		} catch (e){
			console.log('error');
		}

		try {
			var result = Array.prototype.reverse.call("input", " ").join(" ");
			console.log(result);
		} catch (e){
			console.log('error');
		}
	},

	objects: function(){
		var f = function(){
			return
			{
				x: 'one'
			};
		};
		var g = function(){return {x: 'two'};}();
		var h = {x: 'three'};
		console.log((f() || g || h).x);
	}
};

for (task in tasks){
	console.group(task);
	tasks[task]();
	console.groupEnd();
}