好久没写博客了。
这是一个关于寻找质数的故事。

  const eratosthenes = function (n: number) {
    // Eratosthenes algorithm to find all primes under n
    const array = [],
      upperLimit = Math.sqrt(n),
      output = [];

    // Make an array from 2 to (n - 1)
    for (let i = 0; i < n; i++) {
      array.push(true);
    }

    // Remove multiples of primes starting from 2, 3, 5,...
    for (let i = 2; i <= upperLimit; i++) {
      if (array[i]) {
        for (let j = i * i; j < n; j += i) {
          array[j] = false;
        }
      }
    }

    // All array[i] set to true are primes
    for (let i = 2; i < n; i++) {
      if (array[i]) {
        output.push(i);
      }
    }

    return output;
  };

完全借鉴于 sieve-of-eratosthenes-algorithm-in-javascript-running-endless-for-large-number