javascript program to check that the given positive integer is Prime or not?

//javascript program to check that the given positive integer is Prime or not?

function isPrimeNum(num)
{
let b=1;
if(num<2)
{
b=0;
}
for(let div=2;div*div<=num;div++)
{
if(num%div===0)
{
b=0;
break;
}
else
{
continue;
}
div++;
}
return b;
}
var num=97;
var b=isPrimeNum(num);
if(b)
{
console.log(num," is a prime number.");
}
else
{
console.log(num," is not a prime number.");
}