AsyncFunction.apply is not a function

Question

Running following code causes apply(...) is not a function and I'm not sure why.

I feel like invoking apply for async functions not possible. What's correct way then to get apply like calling behavior?

async function throwSomething() {
  return "Apple";
}

async function caughtSomething() {
  try {
     return await throwSomething.apply(this, arguments || [])();
  } catch(e) {
     console.log(e);
  }
}

caughtSomething();

Because, as the error message says, `throwSomething.apply(this, arguments || [])` isn’t a function. Why do you think this `.apply` call results in a function? This has nothing to do with `async`–`await`. Try `function f(){ return ""; }` `f.apply()();`. See the [documentation](//developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply). — Sebastian Simon, Jun 15 '21 at 11:56
`throwSomething.apply(this, arguments || [])();` -> `throwSomething.apply(this, arguments || []);` or perhaps you wanted to do `throwSomething.bind(this, ...arguments)();` but I'm not sure it makes much sense. — VLAZ, Jun 15 '21 at 12:11

score 2 · Accepted Answer · answered Jun 15 '21 at 12:22

It is possible, you just had an extra () after throwSomething.apply(this, arguments || [])

async function throwSomething() {
  return "Apple";
}

async function caughtSomething() {
  try {
     return await throwSomething.apply(this, arguments || []);
  } catch(e) {
     console.log(e);
  }
}

caughtSomething().then(console.log);

The error says "TypeError: throwSomething.apply(...) is not a function", meaning that the return value of throwSomething.apply(...) isn't a function. If .apply wasn't a function, the error would say "TypeError: throwSomething.apply is not a function.

Related: [TypeError: console.log(…) is not a function](/q/31013221/4642212). — Sebastian Simon, Jun 15 '21 at 12:30

AsyncFunction.apply is not a function

1 Answers1