diff.js

const bushu = (n, arr) => {
      if (n < 10) return;
      if (n > 10000000) return;
      let newArr = [];
      for (let i = 1; i <= n; i++) {
        if (arr.indexOf(i) == -1) {
          newArr.push(i);
        }
      }
      return newArr;
    };
    console.log(bushu(100, [1, 2, 3, 4, 7, 9, 10, 100]));