JS Multiple Nested Try...Catch Blocks

Question

I have a function which needs to perform multiple promises in a strict order, and if any one were to fail, the whole function needs to error out. I'm understanding that I should use a Try...Catch block to catch any exceptions which get thrown.

Currently, I am using a nested try...catch like:

try {
  try {
    code1()
  } catch(err) {
    console.log("Inner 1 ", err)
    throw err
  }

  try {
    code2()
  } catch(err) {
    console.log("Inner 2 ", err)
    throw err
  }
} catch(err) {
  console.log("Outer", err)
} finally {
  console.log("Full Success")
}

The intention here is that if either code1() or code2() were to fail, the outer catch would trigger. If both code1 and code2 were to success, the outer finally block would trigger.

However, it seems, right now, no matter if code1 or code2 succeed, the outer finally is always being trigger in addition to the associated inner catch statements.

Is there any way to get the outer catch to trigger?

@Barmar Oh heck... my readings of the docs made me believe it only executed on success... — Felix Jen
– Felix Jen, Commented Nov 22, 2021 at 23:00
From MDN: Statements that are executed after the try statement completes. These statements execute regardless of whether an exception was thrown or caught. — Barmar
– Barmar, Commented Nov 22, 2021 at 23:03
@Barmer Yep, realized my mistake after re-reading. I stopped at the first sentence... — Felix Jen
– Felix Jen, Commented Nov 22, 2021 at 23:23

Felix Jen · Accepted Answer · 2021-11-22 23:02:38Z

2

Turns out, thanks to @Barmar 's comment, the finally block will always execute, that's why my code was always throwing the finally. Instead, I moved the "full success" into the outer try block.

try {
  try {
    code1()
  } catch(err) {
    console.log("Inner 1 ", err)
    throw err
  }

  try {
    code2()
  } catch(err) {
    console.log("Inner 2 ", err)
    throw err
  }

  console.log("Full Success")
} catch(err) {
  console.log("Outer", err)
}

Now, it appears to be working as intended.

answered Nov 22, 2021 at 23:02

Felix Jen

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