javascript - 我怎样才能只使用一次传播？

Question

我该如何改进此代码？

const { first, second, three, ...list } = minerals
    let newMinerals
    if (currentUnit === 'rd') {
      newMinerals = {
        ...list,
        first: first * 9.8,
        second: second * 9.8,
        three: three * 9.8,
      }
    }
    if (currentUnit === 'ch') {
      newMinerals = {
        ...list,
        first: first / 9.8,
        second: second / 9.8,
        three: three / 9.8,
      }
    }

我有两个块，一个是乘法，第二个是除法，我该如何改进？

Answer 1

我会使用一个根据 currentUnit 改变的回调函数来更改和迭代它以仅转换这些属性，从而创建一个属性数组。和 Object.fromEntries :

const cb = currentUnit === 'rd'
    ? v => v * 9.8
    : currentUnit === 'ch'
      ? v => v / 9.8
      : null;
const props = ['first', 'second', 'third'];
const newMinerals = !cb ? null : {
    ...minerals,
    ...Object.fromEntries(
        props.map(
            prop => [prop, cb(minerals[prop])]
        )
    )
};

如 currentUnit总是一个或另一个，它要简单得多:

const currentUnit = 'ch';
const minerals = {
  first: 33,
  second: 44,
  third: 55,
  other: 'someother'
};

const cb = currentUnit === 'rd' ? v => v * 9.8 : v => v / 9.8;
const props = ['first', 'second', 'third'];
const newMinerals = {
    ...minerals,
    ...Object.fromEntries(
        props.map(
            prop => [prop, cb(minerals[prop])]
        )
    )
};
console.log(newMinerals);