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Rooted by: Factorial In Javascript
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  • Description

    Be careful! You were previously implicitly defining a global fact when you really should not have done that. A lot of these problems can be solved by including that "use strict"; at the start of a function, which is especially important when you're starting out. Also, factorial of 0 is 1, and factorial of negatives is undefined. It's also nice to have proper indentation to make programs a little easier to read.

     Code 
    function factorial (n) {
  "use strict";
  if (n < 0) {
    return NaN
  }
  let i, fact
  i = fact = 1
  while (i <= n) { 
    fact *= i
    i++
  }
  return fact
}
     Test Cases 
    const chai = require("chai");
const assert = chai.assert;

describe("Solution", function() {
  it("should test for something", function() {
    assert(factorial(0), 1);
    assert(factorial(1), 1);
    assert(factorial(5), 120);
    assert(factorial(8),40320);
    assert(factorial(15),1307674368000);
  });
});
    View Run Output
  • Code
    • function factorial (n) {
    • if (n <= 0) return 0
    • let i = fact = 1
    • "use strict";
    • if (n < 0) {
    • return NaN
    • }
    • let i, fact
    • i = fact = 1
    • while (i <= n) {
    • fact *= i
    • i++
    • fact *= i
    • i++
    • }
    • return fact
    • }
     Test Cases
    • const chai = require("chai");
    • const assert = chai.assert;
    • describe("Solution", function() {
    • it("should test for something", function() {
    • assert(factorial(0), 1);
    • assert(factorial(1), 1);
    • assert(factorial(5), 120);
    • assert(factorial(8),40320);
    • assert(factorial(15),1307674368000);
    • });
    • });