How to Efficiently Determine if a Number is Prime in JavaScript?

Prime Number Checking in JavaScript

This article addresses the problem of determining if a given number is prime or not using JavaScript. A prime number is an integer greater than 1 that is not divisible by any other natural number except 1 and itself.

Solution 1

The traditional method involves iterating from 2 to the square root of the input number and checking if the number is divisible by any of these. If it is, it's not prime; otherwise, it is.

<code class="javascript">let inputValue = 7;
let isPrime = inputValue == 1 ? false : true; // because 1 is not prime

for (let i = 2; i <p><strong>Time Complexity: O(sqrt(n))</strong><br><strong>Space Complexity: O(1)</strong></p>
<p><strong>Solution 2</strong></p>
<p>An alternative approach utilizes the fact that a prime number greater than 2 cannot be odd. Thus, it suffices to check divisibility by 2 and then by odd numbers up to the square root of the input number. This optimization reduces the execution time significantly.</p>
<pre class="brush:php;toolbar:false"><code class="javascript">const isPrime = num => {
  if (num <p><strong>Time Complexity: O(sqrt(n))</strong><br><strong>Space Complexity: O(1)</strong></p></code>

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