How Can I Find Prime Numbers Between 0 and 100 in JavaScript?

Finding Prime Numbers Between 0 and 100 in JavaScript

Identifying prime numbers within a given range can be a challenging task. While it may seem intuitive to check each number individually by using the modulus operator, this approach becomes inefficient, especially for larger ranges.

An Alternative Approach: Sieve of Eratosthenes

A more efficient algorithm for this problem is the Sieve of Eratosthenes. This method operates by iteratively eliminating non-prime numbers from a list of possible primes.

Implementation in JavaScript

<code class="javascript">function getPrimes(max) {
    var sieve = [], i, j, primes = [];
    for (i = 2; i <= max; ++i) {
        if (!sieve[i]) {
            // i has not been marked -- it is prime
            primes.push(i);
            for (j = i << 1; j <= max; j += i) {
                sieve[j] = true;
            }
        }
    }
    return primes;
}</code>

Usage

To find all prime numbers between 2 and 100:

<code class="javascript">var primes = getPrimes(100);
console.log(primes);</code>

Output:

[ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 ]

Conclusion

Using the Sieve of Eratosthenes provides a highly efficient and reliable method for finding prime numbers within a specified range. This approach dramatically improves performance compared to trial division and enables the identification of primes for even larger ranges.

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