JSFiddle - React, Tailwind, and code Playground

by alekskorovin

JavaScript

//#181_findPrime
function promptIntG1() {
    for (;;) {
        var max = +prompt("Enter interger greater than 1 please", "");
        if ((max > 1) && ((max ^ 0) === max)) return max;
    }
}

function arrPrimes(num) {
    var primeSet = [];
    var mask = [];
    for (var i = 2; i <= num; i++) {
        if (i <= Math.sqrt(num)) {
            if (mask[i]) continue;
            primeSet.push(i);
            for (var j = i; j <= num; j += i) mask[j] = true;
        }
        if (!mask[i]) primeSet.push(i);
    }
    return primeSet;
}

function sumArr(arr) {
    var sum = 0;
    for (var i = 0; i < arr.length; i++) {
        sum += arr[i];
    }
    return sum;
}

var numMax = promptIntG1();
var date = new Date();
var primes = arrPrimes(numMax);
var delta = new Date() - date;

alert(primes.length.toLocaleString() + " Рrimes up to  " + numMax.toLocaleString() +
    "  ( " + delta.toLocaleString() + " ms ): \n" + primes.join(", ") +
    "\n\nThe Sum of these Primes:  " + sumArr(primes).toLocaleString());