tc39 / proposal-optional-catch-binding

proposal for ECMAScript to allow omission of the catch binding

This proposal makes a grammatical change to ECMAScript, allowing the omission of a catch binding in cases where the binding would not be used. This occurs frequently with patterns such as

try {
  // try to use a web feature which may not be implemented
} catch (unused) {
  // fall back to a less desirable web feature with broader support
}

or

let isTheFeatureImplemented = false;
try {
  // stress the required bits of the web API
  isTheFeatureImplemented = true;
} catch (unused) {}

or

let parseResult = someFallbackValue;
try {
  parseResult = JSON.parse(potentiallyMalformedJSON);
} catch (unused) {}

and it is a common opinion that variables which are declared or written to but never read signify a programming error.

The grammar change introduced by this proposal allows for the catch binding and its surrounding parentheses to be omitted, as in

try {
  // ...
} catch {
  // ...
}

See the the full text of the proposal for more info.