console.log(5 % 2);  //5 = 2 * 2 + 1
console.log(8 % 3);  //8 = 2 * 3 + 2
console.log(6 % 2);  //6 = 2 * 3 + 0
console.log(7 % 2);  //7 = 2 * 3 + 1

● 我们可以利用这个特性来判断一个数是奇数还是偶数

const isEven = n =>
  n % 2 === 0 ? console.log(`${n}是偶数`) : console.log(`${n}是奇数`);
isEven(5);
isEven(8);

实例

● 通过奇数偶数判断，将奇数行赋予一种颜色，将偶数行赋予另一种颜色

labelBalance.addEventListener('click', function () {
  [...document.querySelectorAll('.movements__row')].forEach(function (row, i) {
    i % 2 === 0
      ? (row.style.backgroundColor = 'orangered')
      : (row.style.backgroundColor = 'blue');
  });
});