Does arg and something do the same thing in this?

Question

I know a lot of people get confused with this and I'm one of them. I think I'm getting close to understanding but I just can't connect the dots.

function exec (func, arg) {
   func(arg);
};

exec ((something) => {
   console.log(something);
}, "Hi, there");

I don't understand what is happening. I understand that the anonymous function with the something parameter is in the place of the func parameter from the exec function. But what is the point of the arg and the something. Aren't they essentially the same thing here? We are asking that the console logs (something) but what it logs is arg.

Answer 1 · 2020-08-30T18:58:24Z

August 30, 2020 6:58pm

To illustrate why you need the something parameter, you should just try and see how this would run if you took away the something paramter.

exec(() => console.log(), "hi there")

Nothing will happen. exec will always pass an argument arg to func, so the function passed must accept a parameter. If it doesn't, then exec can't actually pass an argument to it. So whatever callback you pass to it, it must accept at least one argument or it won't work as intended. I hope that makes sense. This is a bit tricky and I even had to think about it for a minute.

A word of consolation though: I've gone all through the techdegree and worked on a lot of independent projects, and never once have I had a use case for writing a function like this. This is more of a brain teaser that is good to wrestle with, but I don't think it has many practical applications.

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Daniel L.

Daniel L.

Does arg and something do the same thing in this?

1 Answer

Michael Cook

Michael Cook

Daniel L.

Daniel L.

Michael Cook

Michael Cook