Is it possible to create an inline try without a catch like shown

Question

I have this case where I want to run code that may have an error but I don't need to catch it.

If the response is not valid JSON then the result should be 0:

I'd like to use this code:

var overallProgress = try {JSON.parse(text)} ? 0;

Is it possible to the above?

Or something like this:

var overallProgress = try { JSON.parse(text)} catch(error) { 0 }; 
var overallProgress = try { JSON.parse(text)} catch(error) { overallProgress = 0 };

There are errors using the code above.

I found this related post below but no answer.

Is try {} without catch {} possible in JavaScript?

For anyone whose eyes I've hurt:

var overallProgress = 0; 
try { overallProgress = JSON.parse(text).overallProgress } 
catch(error) { overallProgress = 0 };

@Bergi ackshually, i could define progress as zero beforehand and update the value only if — 1.21 gigawatts, May 28 '23 at 00:31
@1.21gigawatts and then still you need to catch the exception (to ignore it, by *not* updating the progress variable). — Bergi, May 28 '23 at 16:05
@Bergi this makes me think a `JSON.verifyValidJSONString(mystring)` would be useful — 1.21 gigawatts, May 29 '23 at 00:37
@Bergi the reason for the JSON.validate() method would be so you could avoid the try catch block conundrum — 1.21 gigawatts, May 29 '23 at 17:00
@1.21gigawatts You mean `const overallProgress = JSON.validate(text) ? JSON.parse(text) : 0`? That would have to parse the JSON string twice. — Bergi, May 29 '23 at 18:10
@Bergi you presented another use case. the use of trinary support. my json is about 200 characters. so 1/100000000 of a second to parse. that's ok — 1.21 gigawatts, May 29 '23 at 18:15
If not using it for a conditional, what did you propose `validate` and `verifyValidJSONstring` methods for? — Bergi, May 29 '23 at 18:21
@Bergi I misunderstood. That's exactly what I would use it for or the predefine the value and update the value only if JSON is valid case. — 1.21 gigawatts, May 29 '23 at 18:38

Bergi · Answer 1 · 2023-05-28T16:06:52.617

Not directly, no. But you can use an IIFE:

const overallProgress = (() => { try { return JSON.parse(text) } catch { return 0 } })();

I'd still format it as multiple lines though:

const overallProgress = (() => {
  try {
    return JSON.parse(text);
  } catch {
    return 0;
  }
})();

Apart from being able to use const, it doesn't really have an advantage over simply using two assignments:

let overallProgress;
try {
  overallProgress = JSON.parse(text);
} catch {
  overallProgress = 0;
}

or even

let overallProgress = 0;
try {
  overallProgress = JSON.parse(text);
} catch {
  /* ignore: keep `overallProgress` value */
}

Is it possible to create an inline try without a catch like shown

1 Answers1