I've created a loop in JS to calculate factorials - however, instead of getting the factorial, I'm just only getting the first value of the for loop. In the code below, I'm just getting 1 for FirstFactorial(5);.

Any ideas on what's wrong here...?

function FirstFactorial(num) {
  var myVar = 1;
  for (var i = 1; i <= num; i++) {
    myVar = myVar * i;
    return myVar;
  }
};

console.log(FirstFactorial(5));

I've created a loop in JS to calculate factorials - however, instead of getting the factorial, I'm just only getting the first value of the for loop. In the code below, I'm just getting 1 for FirstFactorial(5);.

Any ideas on what's wrong here...?

function FirstFactorial(num) {
  var myVar = 1;
  for (var i = 1; i <= num; i++) {
    myVar = myVar * i;
    return myVar;
  }
};

console.log(FirstFactorial(5));

• javascript
• loops
• for-loop

• 5 you should look up recursion... because you are attempting to do it, but you aren't – El Guapo Commented May 6, 2014 at 19:21
• move the return statement outside of your for loop, it will stop executing when you hit a return statement and not actually loop. – doublesharp Commented May 6, 2014 at 19:22
• also more standard to use a lower case for functions, capitalize objects, so firstFactorial() would be a more appropriate name. – doublesharp Commented May 6, 2014 at 19:23

4 Answers 4

Your loop actually returns when it first reaches the return and never runs after. This is how return works, returning back to where it was called. You would be better to place your return to run AFTER the loop has pleted.

function FirstFactorial (num) { 
  var myVar=1;
  for(var i=1; i<=num; i++){
    myVar=myVar*i;
  }
  return myVar;
};

show(FirstFactorial(5));

Here is a JSFiddle of the result.

By using recursion, you can achieve much smaller code and eliminate the need for a for loop:

function factorial(n) { 
    return n > 1 ? n * factorial(n-1) : (n == 0) ? 1 : n;
}

console.log(factorial(5));

Returns:

120

jsFiddle: http://jsfiddle/DuLpr/2/

You need to have your return statement outside of the loop:

function FirstFactorial (num) { 
    var myVar=1;
    for(var i=1; i<=num; i++){
        myVar=myVar*i;

    }
    return myVar;
};

Take the return statement outside of your for loop:

function FirstFactorial (num) { 
  var myVar=1;
  for(var i=1; i<=num; i++){
    myVar=myVar*i;
    }
return myVar;
};

show(FirstFactorial(5));