如何使用基于另一个数组的值过滤对象数组

Question

我有两个数组，第一个包含对象，第二个包含id。 我想从第一个数组返回一个新数组，该数组包含来自第一个数组的id。 这样做的最佳和最有效的方法是什么？

const firstArr = [{id: 1, city: London}, {id: 5, city: 'Berlin'}, {id: 10, city: 'Paris'}, {id: 2, city: 'Rome'}]

const secondArr = ['2', '5']

const wantedArr = [{id: 2, city: 'Rome'}, {id: 5, city: 'Berlin'}]

Answer 1

对于线性时间复杂度，将第二个数组转换为set，然后使用Set.prototype.has

 const firstArr = [{id: 1, city: 'London'}, {id: 5, city: 'Berlin'}, {id: 10, city: 'Paris'}, {id: 2, city: 'Rome'}] const secondArr = ['2', '5']; let set = new Set(secondArr); const res = firstArr.filter(x => set.has(String(x.id))); console.log(res) 

如果您想根据，以保持结果排列的顺序secondArr那么首先从做一个对象firstArr ，然后使用map()上secondArr

 const firstArr = [{id: 1, city: 'London'}, {id: 5, city: 'Berlin'}, {id: 10, city: 'Paris'}, {id: 2, city: 'Rome'}] const secondArr = ['2', '5']; const obj = firstArr.reduce((ac,a) => (ac[a.id] = a,ac), {}); const res = secondArr.map(x => obj[x]); console.log(res) 

Answer 2

您可以使用.indexOf()或.includes()方法实现此.indexOf()

 const firstArr = [{ id: 2, city: 'London' }, { id: 2, city: 'Tokyo' }, { id: 5, city: 'Berlin' }, { id: 10, city: 'Paris' }, { id: 6, city: 'Rome' }]; const secondArr = ['2', '5']; const output = firstArr.filter((r) => { return secondArr.includes(`${r.id}`); }); console.log(output); 

 const firstArr = [{ id: 2, city: 'London' }, { id: 2, city: 'Tokyo' }, { id: 5, city: 'Berlin' }, { id: 10, city: 'Paris' }, { id: 6, city: 'Rome' }]; const secondArr = ['2', '5']; const output = firstArr.filter((r) => { return secondArr.indexOf(`${r.id}`) > -1; }); console.log(output); 

Answer 3

这应该做的伎俩：

secondArr.map(e => firstArr.filter(a => a.id == +e))

我正在使用+e将字符串转换为int，可能不是最好的方法，但肯定是最短的。

Answer 4

const wantedArr = firstArr.filter(({ id }) => secondArr.includes(`${id}`));