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JavaScript: Check whether the provided integer is a prime number or not

JavaScript fundamental (ES6 Syntax): Exercise-191 with Solution

Write a JavaScript program to check whether the provided integer is a prime number or not.

  • Check numbers from 2 to the square root of the given number.
  • Return false if any of them divides the given number, else return true, unless the number is less than 2.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const isPrime = num => {
  const boundary = Math.floor(Math.sqrt(num));
  for (var i = 2; i <= boundary; i++) if (num % i === 0) return false;
  return num >= 2;
};

console.log(isPrime(11));
console.log(isPrime(17));
console.log(isPrime(8));

Sample Output:

true
true
false

Pictorial Presentation:

JavaScript Fundamental: Check whether the provided integer is a prime number or not.

Flowchart:

flowchart: Check whether the provided integer is a prime number or not

Live Demo:

See the Pen javascript-basic-exercise-191-1 by w3resource (@w3resource) on CodePen.


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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