How to Efficiently Find Prime Numbers Within a Range in JavaScript?

Efficiently Find Prime Numbers within a Range

In JavaScript, identifying prime numbers between a specified range can be achieved through various methods. One commonly used approach is the Sieve of Eratosthenes algorithm. This technique marks multiples of primes as non-prime, allowing for the efficient identification of prime numbers.

The following is a JavaScript implementation of a modified Sieve of Eratosthenes algorithm to find prime numbers within the range of 0 to 100:

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;
}

In this function, an array named 'sieve' is used to track numbers marked as non-prime. Iterating through numbers from 2 to the maximum specified, unmarked numbers are considered prime and added to the 'primes' array. Multiples of primes are subsequently marked as non-prime in the 'sieve' array.

By utilizing this function, you can efficiently retrieve all prime numbers within a specified range. For instance, getPrimes(100) will return an array of all primes between 2 and 100 (inclusive).

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