javascript - 或循环中 If 语句中的 boolean 表达式

Question

当我通过 Or boolean 语句检查数字是否为质数时，它没有完成检查，而是返回整个数组。

function sumPrimes(num) {
  var arr = [];

  var prime;
  for(var i = 1; i <=num; i++){
   if(i%2 !== 0 || i%3 !== 0 || i%5 !== 0){
     arr.push(i);
   }
  }
  return arr;
}

sumPrimes(10);

Answer 1

我建议你只买一个 "get prime numbers algorithm"像这样:

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;
}

然后使用 reduce 总结

var sumPrimes = function(num) {
  var primes = getPrimes(num)
  var sum = primes.reduce(function(sum, prime) {
    return sum + prime
  }, 0)
}