JavaScript function as argument of function on a variable?

Question

Here's what I have:

function verificarNumero(test, num) {
    return (test(num));
};

var resultadoTesteMultiplos = verificarNumero(function (num){return (num % 10 == 0);}, num1);

This function is supposed to find out if a number is a multiple of 10. I know there are simpler ways to do it, but I really want to make this work.

I want to be able to do something like console.log(resultadoTesteMultiplos(10)); but the console returns "resultadoTesteMultiplos is not a function", and "num1 is undefined."

What am I doing wrong?

I'm passing it as an argument, so I don't need to define it... right? — Igor Sílva
– Igor Sílva, Commented Mar 21, 2017 at 9:53
@IgorSílva — Only if you are happy with the value being undefined when the function you are passing it to receives it (and you haven't declared it either, so you'll get a ReferenceError for that). — Quentin
– Quentin, Commented Mar 21, 2017 at 9:54
Why do you want to wrap a function you created im a function? — Bálint
– Bálint, Commented Mar 21, 2017 at 9:55

Dan D. · Accepted Answer · 2017-03-21 09:55:07Z

4

Sounds like you meant to curry but only got half way:

function verificarNumero(test) {
  return function(num) {
    return test(num);
  };
}

var resultadoTesteMultiplos = verificarNumero(function(num) {
  return (num % 10 == 0);
});

console.log(resultadoTesteMultiplos(10));

answered Mar 21, 2017 at 9:55

Dan D.

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Ionut Necula · Accepted Answer · 2017-03-21 09:53:21Z

2

If you define num1 variable your code should work and the type of the resultadoTesteMultiplos is boolean. See the working snippet below please:

var num1 = 10;
function verificarNumero(test, num) {
  return (test(num));
};

var resultadoTesteMultiplos = verificarNumero(function(num) {
  return (num % 10 == 0);
}, num1);
console.log(typeof resultadoTesteMultiplos);
console.log(resultadoTesteMultiplos);

answered Mar 21, 2017 at 9:53

Ionut Necula

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2 Comments

Igor Sílva Over a year ago

Yes i tried that, what i wanted was to pass a value to num1 without having to set it like that.

Ionut Necula Over a year ago

@IgorSílva, ok, I understand. The above answer should work too, but I see the difference between mine an the accepted answer and I'm happy you found what you needed.

David Barker · Accepted Answer · 2017-03-21 10:00:17Z

0

Return a function from verificarNumero, not the result of the function.

function verificarNumero (cb) {
    return function (num) {
        return cb.apply(this, [num]);
    }    
};

resultadoTesteMultiplos = verificarNumero(function (num) {
    return (num % 10 == 0);
};

console.log(resultadoTesteMultiplos(10));

answered Mar 21, 2017 at 10:00

David Barker

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