Question 357956 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – How to execute multiple other cases inside of a case

So it is possible to fall-through the case to another case:

switch(variable) {
  case 1:
    // do something 1
  case 2:
    // do something 2
    break;
  case 3:
    // do something 3
    break;
}

But what if we would want to execute multiple other cases after finishing the main case, or execute other case that is not directly after the main case?
Pseudocode for example:

switch(variable) {
  case 1:
    // do something 1
    break;
  case 2:
    // do something 2
    break;
  case 3:
    // do something 3
    execute case 2;
    execute case 1;
    break;
}

I’ve researched the option of labeled statements, but it’s not gonna work here it seems.
The only option I see here is to create new function for every case, but I’m wondering – is there better, cleaner, more readable and/or shorter option?

I’m looking for all tips – be it some keyword I’m missing, your personal tips to do it cleanly, or libraries and even propositions from other languages like typescript etc.

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    Nick Parson gave this awesome idea:

    Maybe wrap the whole switch in a function that accepts variable and do a recursive call?

    Which works perfectly in this situation; So to incorporate it to example I posted and accept it as an answer:

    mySwitch(variable);
function mySwitch(_v) {
  switch(_v) {
    case 1:
      // do something 1
    break;
    case 2:
      // do something 2
    break;
    case 3:
      // do something 3
      mySwitch(2);
      mySwitch(1);
    break;
  }
}

    It's clean, does the trick... and moreover - if you declare function where switch statement normally would be (in example inside some outer function), you will be able to change variables declared in the outer function, just like you would be able to inside switch statement.

    (I will accept this as an answer in 2 days, to have this question marked as answered, unless Nick will post their own answer for credit)


  2. 0

    From my above comment …

    How about using named functions? … like doSomething_1, doSomething_2, doSomething_3 where the latter is implemented like this … function doSomething_3() { doSomething_2(); doSomething_1(); }, and where one does invoke exactly one case specific function for each matching case.

    Since the OP clearly is in control of the switch-case related code, why not implementing each case specific handling as own function. Thus, firstly decoupling the implementation of the case specific handling from the mySwitch function (the one of the OP’s own answer) and secondly enabling code-reuse for the OP’s example code’s 3rd case.

    The next provided example code in my eyes is much easier to comprehend than what the OP did come up with in his own answer …

    function mySwitch(value) {
  switch (value) {
    case 1:
      handleCase1();
      break;
    case 2:
      handleCase2();
      break;
    case 3:
      handleCase3();
      break;
  }
}
console.log('mySwitch(1) ...');
mySwitch(1);

console.log('mySwitch(2) ...');
mySwitch(2);

console.log('mySwitch(3) ...');
mySwitch(3);
    .as-console-wrapper { min-height: 100%!important; top: 0; }
    <script>
function handleCase1() {
  console.log('handling case 1');
}
function handleCase2() {
  console.log('handling case 2');
}
function handleCase3() {
  console.log('handling case 3 which invokes handling of 2 and 1');

  handleCase2();
  handleCase1();
}
</script>

    … and in case the switch value is clearly either string or number based, one could shorten the above mySwitch function to …

    function mySwitch(value) {
  ({
    '1': handleCase1,
    '2': handleCase2,
    '3': handleCase3,
  })[String(value)]?.();
}
console.log('mySwitch(0) ...');
mySwitch(0);

console.log('mySwitch(1) ...');
mySwitch(1);

console.log('mySwitch(2) ...');
mySwitch(2);

console.log('mySwitch(3) ...');
mySwitch(3);

console.log('mySwitch(4) ...');
mySwitch(4);
    .as-console-wrapper { min-height: 100%!important; top: 0; }
    <script>
function handleCase1() {
  console.log('handling case 1');
}
function handleCase2() {
  console.log('handling case 2');
}
function handleCase3() {
  console.log('handling case 3 which invokes handling of 2 and 1');

  handleCase2();
  handleCase1();
}
</script>
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