Using and catching RangeError in javascript

Question

I'm about to throw an exception using RangeError and wanted to check that I'm using it correctly and how to best catch it.

I have a function that could throw a RangeError OR a TypeError like this

function saveNumber(val) {
  // Only accept numbers.
  if (typeof val !== 'number') {
    throw new TypeError();
  }

  // Error if the number is outside of the range.
  if (val > max || val < min) {
    throw new RangeError();
  }

  db.save(val);
}

I'd like to call it and only deal with the RangeError. What's the best way to do this?

another piece of code may want to call this function and deal with the TypeError — eddiec, Dec 03 '13 at 15:45

score 12 · Accepted Answer · edited May 23 '17 at 11:54

12

try {
  saveNumber(...);
} catch (e) {
  if (e instanceof TypeError) {
    // ignore TypeError
  } 
  else if(e instanceof RangeError) {
    // handle RangeError
  }
  else {
    // something else
  } 
}

source

edited May 23 '17 at 11:54

Community

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answered Dec 03 '13 at 15:47

qwertynl

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In general you need to re-throw if you don't handle. – Roly Sep 14 '15 at 21:26

score 4 · Answer 2 · edited Oct 31 '18 at 14:30

4

Straight from the MDN documentation on try - catch:

try {
    saveNumber(...);
} catch (e is instanceof RangeError) {
    // Do something
} catch (e) {
    // re-throw whatever you don't want to handle
    throw e;
}

edited Oct 31 '18 at 14:30

Snake Eyes

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answered Dec 03 '13 at 15:48

Justin Niessner

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JS Hint is complaining 'catch filter' is only available in Mozilla JavaScript extensions (use moz option)'. So it's a nice answer but not fully compatible. – eddiec Dec 03 '13 at 16:09
From the same docs: "Reminder: this functionality is not part of the ECMAScript specification." – Pavlo Jul 13 '16 at 12:21

score 2 · Answer 3 · answered Oct 24 '17 at 10:27

2

slightly more elegant answer:

switch (error.constructor) {
    case NotAllowedError:
        return res.send(400);
    case NotFoundError:
        return res.send(404);
    default:
        return res.send(500);
}

answered Oct 24 '17 at 10:27

Anona112

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Using and catching RangeError in javascript

3 Answers3