JS Use 6N±1 Method to Find Prime Numbers Example Tutorial_Javascript Skills

Use the 6N±1 method to find prime numbers
Any natural number can always be expressed in one of the following forms:
6N, 6N 1, 6N 2, 6N 3, 6N 4, 6N 5 (N=0, 1, 2,...)
Obviously, when N≥1, 6N, 6N 2, 6N 3, 6N 4 are not prime numbers. Only natural numbers in the form of 6N 1 and 6N 5 may be prime numbers. Therefore, except for 2 and 3, all prime numbers can be expressed in the form of 6N±1 (N is a natural number).
Based on the above analysis, we can construct another sieve to screen only natural numbers in the shape of 6 N±1. This can greatly reduce the number of screenings and further improve the operating efficiency and speed of the program.
The following code requires a natural number greater than 10

Copy code The code is as follows:

function fn( num){
var arr = [];
arr.push(2);
arr.push(3);
arr.push(5);
arr.push(7 );
var t = 0;
for (var i = 3; t < num; i = i 3) {
for (var j = 0; j < 2; j ) {
t = 2 * (i j) - 1;
if (t < num && (t % 5 == 0 ? false : t % 7 == 0 ? false : true)) {
arr. push(t);
}
}
}
return arr.join(” “);
}
document.write(fn(1000));

If you guys have any more efficient methods or if there is something wrong with the above code, please point it out.