if statement - javascript syntax questioon

Question

So let's say I have the following code:

function c (f,i) {
  let x = i;
  if (f(x,i)){
     x--;
  }
  if (f(x,2)) {
     console.log(1);
  }
  else {
     console.log(2);
  }
}

what exactly happens in the if statements, I don't understand the syntax behind it. f is no function, it's a variable, so what happens here? does it equal to f * ( x * i)? whats the operands behind this syntax. Thanks in advance

Answer 1

A variable can also hold a function. It's possible to call c like this:

c(function(x, i) {/* do some check with x and i */}, 10);

In the if statements, the function you pass is called to do a check. A function like this is called a callback function. You have to pass it to the c function as in the example above. So if you call c, you can also determine how the check is done that c does.