Write a function to return the factorial of a number.
Factorial of a number is given by :
n! = n * (n-1) * (n-2) * ..... * 1For example : 3! = 3*2*1 = 6 4! = 4*3*2*1 = 24
Note : 0! = 1
factorial
is a function.
testString: assert(typeof factorial === 'function', 'factorial
is a function.');
- text: factorial(2)
should return a number.
testString: assert(typeof factorial(2) === 'number', 'factorial(2)
should return a number.');
- text: factorial(3)
should return 6.
testString: assert.equal(factorial(3),results[0],"factorial(3)
should return 6.");
- text: factorial(3)
should return 120.
testString: assert.equal(factorial(5),results[1],"factorial(3)
should return 120.");
- text: factorial(3)
should return 3,628,800.
testString: assert.equal(factorial(10),results[2],"factorial(3)
should return 3,628,800.");
```