Dynamically adding cases to a switch

Question

I need to dynamically add cases to a switch. I want the user to be able to add items and every item needs it\'s own switch case.

Answer 1

This was the best solution for my needs, but works only with a limited number of custom cases:

var cases = [false, false];

switch(condition) {
    case cases[0]:
        doStuff();
        break;
    case cases[1]:
        doSomethingElse();
        break;
}

Now, you can dynamically change the values in the array cases, and the condition in the switch case will be triggered respectively;

You can click the above snippet to see it working ;)

const cases = [false, false]; // shall be defined
  
$('#option1').click( function() {
  cases = [38,37];
});

$('#option2').click( function() {
  cases = [39,40];
});

$(window).keydown( function(e) {
  switch (e.keyCode) {
     case 32:
        $("body").append('space<br>');
        break;
     case cases[0]:
        $("body").append((e.keyCode == '38' ? 'UP' : 'RIGHT' ) + '<br>');
        break;
     case cases[1]:
        $("body").append((e.keyCode == '37' ? 'LEFT' : 'DOWN' ) + '<br>');
        break;

  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

At the begining the switch only take in account SPACE keyCode<br>
-if you click option1 then it recognize UP and LEFT<br>
-if you click option2, the aboves are replaced with RIGHT and DOWN<br><br>

<div id='option1'>OPTION 1</div>
<div id='option2'>OPTION 2</div>

Answer 2

You can use object with callback functions instead:

var callbacks = {};

function add(_case, fn) {
   callbacks[_case] = callbacks[_case] || [];
   callbacks[_case].push(fn);
}

function pseudoSwitch(value) {
   if (callbacks[value]) {
      callbacks[value].forEach(function(fn) {
          fn();
      });
   }
}

and you can add new entry using:

add('something', function() {
   // case for something
});