Factorialize in JS

Question

Can someone explain to me how this works?
```
function factorialize(num) {
  if (num === 0 || num === 1) {
    return 1;                 
  }
  return num * factorialize(num-1);
}
factorialize(5);
```
This is supposed to return 120, 3628800, 2432902008176640000, and 1.  Apparantly it works but I just don't understand how.

rydavim · Accepted Answer

I'm a bit confused, because the code you linked should only return 120 - none of the other numbers. Maybe there are other calls that aren't in the code you pasted here?
When you run into code that is confusing, it's often helpful to add print statements to the console so you can follow what's happening.
Try running the following code instead, and taking a look at what prints out to the console. 
```javascript
function factorialize(num) {
  if (num === 0 || num === 1) { // If the current num is 0 or 1, return 1.
    console.log("The current value of num is: " + num);
    return 1;
  }
  console.log("The current value of num is: " + num);
  return num * factorialize(num - 1); // Otherwise, return num * (num - 1);
}
console.log("This program will print out the current value of num each time the facrotialize function is called.");
console.log("The function works by multiplying each of these values together recursively.");
console.log("The factorial of 5 is: " + factorialize(5));
```

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Ira Salem

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Factorialize in JS

1 Answer

rydavim

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Ira Salem

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rydavim

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