22 lines
492 B
Markdown
22 lines
492 B
Markdown
---
|
|
title: isPrime
|
|
tags: math,algorithm,beginner
|
|
---
|
|
|
|
Checks if the provided integer is a prime number.
|
|
|
|
- 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`.
|
|
|
|
```js
|
|
const isPrime = num => {
|
|
const boundary = Math.floor(Math.sqrt(num));
|
|
for (let i = 2; i <= boundary; i++) if (num % i === 0) return false;
|
|
return num >= 2;
|
|
};
|
|
```
|
|
|
|
```js
|
|
isPrime(11); // true
|
|
```
|