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JavaScript: Calculate the factorial of a number

JavaScript fundamental (ES6 Syntax): Exercise-238 with Solution

Write a JavaScript program to calculate the factorial of a number.

  • Use recursion.
  • If n is less than or equal to 1, return 1.
  • Otherwise, return the product of n and the factorial of n - 1.
  • Throw a TypeError if n is a negative number.

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Calculate the factorial of a number</title>
</head>
<body>

</body>
</html>

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const factorial = n =>
  n < 0
    ? (() => {
        throw new TypeError('Negative numbers are not allowed!');
      })()
    : n <= 1
      ? 1
      : n * factorial(n - 1);

console.log(factorial(1));
console.log(factorial(5));
console.log(factorial(7));

Sample Output:

1
120
5040

Pictorial Presentation:

JavaScript Fundamental: Calculate the factorial of a number.
JavaScript Fundamental: Calculate the factorial of a number.

Flowchart:

flowchart: Calculate the factorial of a number.

Live Demo:

See the Pen javascript-basic-exercise-238-1 by w3resource (@w3resource) on CodePen.


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Previous: Write a JavaScript program to generate an array, containing the Fibonacci sequence, up until the nth term.
Next: Write a JavaScript program to escape a string to use in a regular expression.

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JavaScript: Tips of the Day

How to check whether a string contains a substring in JavaScript?

ECMAScript 6 introduced String.prototype.includes:

const string = "foo";
const substring = "oo";

console.log(string.includes(substring));

includes doesn't have Internet Explorer support, though. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found: 

var string = "foo";
var substring = "oo";

console.log(string.indexOf(substring) !== -1);

Ref: https://bit.ly/3fFFgZv