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:
Flowchart:

Live Demo:
See the Pen javascript-basic-exercise-191-1 by w3resource (@w3resource) on CodePen.
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Next: Write a JavaScript program to check whether the provided value is an object created by the Object constructor.
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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
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