Question

54

Javascript scope variable to switch case?

rated 0 times [ 60] [ 6] / answers: 1 / hits: 51082 / 8 Years ago, tue, december 6, 2016, 12:00:00

In C you can scope a variable to a switch case, like this.

With javascript I get unexpected token using the following:

const i = 1



switch (i) {

    // variables scoped to switch

    var s

    var x = 2342

    case 0:

      s = 1 + x

      break

    case 1:

      s = 'b'

      break

}

Is there another way to do this or should I just declare my variables outside the switch?

EDIT:

This is a workaround I considered but it didn't end up working. The reason being that each case has its own scope.

const i = 1



switch (i) {

    case i:

      // variables scoped to switch

      var s

      var x = 2342

    case 0:

      s = 1 + x

      break

    case 1:

      s = 'b'

      break

}

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mercedez

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1 Year ago

answered 8 Years ago daja · Accepted Answer

Since var creates variables at function scope anyway, using it is pretty pointless. For this to work at a granularity below function scopes you'll have to use let and a browser/compiler which supports it, and then introduce a new block which you can scope things to (within switch it's simply invalid syntax):

if (true) {

    let s;



    switch (i) {

        ...

    }

}

This scopes s to the if block, which for all intents and purposes is identical to the switch scope here.

If you cannot support let, you'll need to use an IIFE:

(function () {

    var s;



    switch (...) ...

})();