Identifying a function name or property in Javascript [duplicate]

Question

I'm using an npm module that throws an empty function i.e. UnauthorizedException upon error. I want to be able to identify the function thrown so i can handle it accordingly

function UnauthorizedException() {

}

const f = () => {
  throw (new UnauthorizedException());
};

try {
  f();
} catch (err) {
  // How to identity a function name/property/etc so I can handle the error accordingly
  console.log(err);
  console.log(typeof (err));
}

Ori Drori · Accepted Answer · 2020-05-30 10:15:06Z

3

The UnauthorizedException function is used as constructor. You can check if an object was created from a constructor using the instanceof operator:

function UnauthorizedException() {}

const f = () => {
  throw (new UnauthorizedException());
};

try {
  f();
} catch (err) {
  console.log(err instanceof UnauthorizedException);
}

answered May 30, 2020 at 10:15

Ori Drori

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2 Comments

T.J. Crowder Over a year ago

If this is the answer, though, surely this is a duplicate of this and a bunch of others?

aldred Over a year ago

Sorry I wasn't aware it's a duplicate. Yes that is what I'm looking for i.e. instanceof. Thanks a lot

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