Some of the JavaScript puzzlers from VanJS (2013-07-11), as presented by Charles Bihis of Adobe.

1.js

var commodusRule = 'thumbsUp';
console.log('Maximus the ' + (commodusRule === 'thumbsUp') ? 'Gladiator' : 'Merciful');

// What does this print?

// A. "Maximus the Gladiator"
// B. "Maximus the Merciful"
// C. "Maximus the "
// D. None of the above

2.js

var name = 'World!';

(function() {
  if (typeof name === 'undefined') {
    var name = 'Mr. Bond';
    console.log('Goodbye, ' + name);
  } else {
    console.log('Hello, ' + name);
  }
})();

// What does this print?

// A. "Hello, World!"
// B. "Hello, Mr. Bond"
// C. "Goodbye, Mr. Bond"
// D. "Goodbye, World!"
// E. None of the above

3.js

function doStuff(name) {
  switch (name) {
    case 'A':
      console.log('It is A');
      break;
    
    case 'B':
      console.log('It is B');
      break;
      
    case 'C':
      console.log('It is C');
      break;
    
    default:
      console.log("We don't know!");
      break;
  }
}

doStuff(new String('A'));

// What does this print?

// A. "It is A"
// B. "It is B"
// C. "It is C"
// D. "We don't know"
// E. It varies
// F. None of the above

4.js

var zipcodes = ['39461', '02391', '56910', '09154', '74512'];

for (var i = 0; i < zipcodes.length; i++) {
  if (!isNaN(parseInt(zipcodes[i])) && parseInt(zipcodes[i]) > 0) {
    console.log(parseInt(zipcodes[i]));
  }
}

// What does this print?

/* A. 39461
      19
      56910
      74512
*/
/* B. 39461
      2391
      56910
      9154
      74512
*/
/* C. 39461
      56910
      74512
*/
// D. Error
// E. It varies
// F. None of the above

5.js

var END = 9007199254740992; // Math.pow(2, 53)
var START = END - 100;

var count = 0;
for (var i = START; i <= END; i++) {
  count++;
}

console.log(count);

// What does this print?

// A. 100
// B. 101
// C. Error
// D. None of the above