Using an array through a switch() statement in Javascript

Question

I'm trying to develop a simplified poker game through Javascript. I've listed all possible card combinations a given player might have in its hand ordered by its value, like this:

switch(sortedHand)
{           
 //Pair
     case [1,1,4,3,2]: sortedHand.push(1,"Pair"); break;
     case [1,1,5,3,2]: sortedHand.push(2,"Pair"); break; 
     case [1,1,5,4,2]: sortedHand.push(3,"Pair"); break;
     case [1,1,5,4,3]: sortedHand.push(4,"Pair"); break;
     case [1,1,6,3,2]: sortedHand.push(5,"Pair"); break;
     case [1,1,6,4,2]: sortedHand.push(6,"Pair"); break;
     case [1,1,6,4,3]: sortedHand.push(7,"Pair"); break;
     case [1,1,6,5,2]: sortedHand.push(8,"Pair"); break;
     case [1,1,6,5,3]: sortedHand.push(9,"Pair"); break;
     case [1,1,6,5,4]: sortedHand.push(10,"Pair"); break;

Even though the "sortedHand" array stores values succesfully (as I've seen through console.log), the switch() statement always returns the default case, and everyone gets an straight flush. I fear this is a matter of the literal approach I've used to declare possible array values to be compared with the whole of "sortedHand", but I don't know any better. Is it even possible to use switch() in such a manner?

Answer 1

You can try switching on a textual representation of the array.

switch(sortedHand.join(' '))
{           
    //Pair
    case '1 1 4 3 2': sortedHand.push(1,"Pair"); break;
    case '1 1 5 3 2': sortedHand.push(2,"Pair"); break; 
    case '1 1 5 4 2': sortedHand.push(3,"Pair"); break;
    case '1 1 5 4 3': sortedHand.push(4,"Pair"); break;
    // etc.
}

As an alternative to specifying every case directly, perhaps build a function dispatch table using an object and get rid of the switch entirely.

var dispatch = {};

// Build the table however you'd like, for your application
for (var i = 0; i < 10; i++) {
    (function(i) {
        var hand = ...; // Add your hand logic here
        dispatch[hand] = function() { sortedHand.push(i, "Pair"); };
    })(i);
}

// Execute your routine
dispatch[sortedHand.join(' ')]();

Answer 2

the switch() statement always returns the default case

That's because the comparison doesn't check the array contents, but the array object itself. Objects are considered equal by their identity, so nothing will be equal to an object instantiated by a literal.

Is it even possible to use switch() in such a manner?

Yes, one can use objects in switch statements, but you would have to use references in the cases. Not applicable to your problem.

In your case, I'd suggest a stringification:

switch(sortedHand.join())
{           
 //Pair
     case "1,1,4,3,2": sortedHand.push(1,"Pair"); break;
     case "1,1,5,3,2": sortedHand.push(2,"Pair"); break; 
     case "1,1,5,4,2": sortedHand.push(3,"Pair"); break;
     case "1,1,5,4,3": sortedHand.push(4,"Pair"); break;
     case "1,1,6,3,2": sortedHand.push(5,"Pair"); break;
     case "1,1,6,4,2": sortedHand.push(6,"Pair"); break;
     case "1,1,6,4,3": sortedHand.push(7,"Pair"); break;
     case "1,1,6,5,2": sortedHand.push(8,"Pair"); break;
     case "1,1,6,5,3": sortedHand.push(9,"Pair"); break;
     case "1,1,6,5,4": sortedHand.push(10,"Pair"); break;

but I guess there's an even better, arithmetic solution to detect the patterns you're after. That would be shorter and faster, but I'm not sure what exactly this snippet is supposed to do.