Using class functions as arguments in methods NodeJS

Question

I am trying to use a class function as an argument in another methods. But I keep on getting function not defined when trying to do so. Below is how my class looks like:

class Test{
constructor(name){
this.name = name;
    }

functionA(){
    console.log('My name is John');
    }

functionB(){
    console.log('My name is Steve');
    }

}


function caller(args){
    let test = new Test('t1');
  return test.args;
}

caller(functionA())

I am not sure what to do here. Any help is appreciated. Thanks

random_user_name · Accepted Answer · 2019-06-04 21:07:41Z

1

You need to pass the function name (as a string). Currently you are calling functionA(), which is not a defined function.

See the below altered code:

class Test {
  constructor(name) {
    this.name = name;
  }

  functionA() {
    console.log('My name is John');
  }

  functionB() {
    console.log('My name is Steve');
  }

}


function caller(args) {
  let test = new Test('t1');
  // use bracket notation to CALL the function, and include the () to call
  return test[args]();
}

// pass the function name as a string
caller('functionA')

answered Jun 4, 2019 at 21:07

random_user_name

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Comments

9000 · Accepted Answer · 2019-06-05 16:47:09Z

1

(Not an answer, just an explanation.)

There's no top-level functionA, there's functionA defined inside Test. It's an instance method, so it's not even visible in the namespace of Test (Test.functionA is undefined).

In any case, you'd need to pass functionA (a reference to the function), not functionA() (a reference to the result that calling the function produces).

The cleanest method is indeed what @cale_b suggests.

edited Jun 5, 2019 at 16:47

answered Jun 4, 2019 at 21:22

9000

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