如何使用reduce获取列表数组对象的一些道具

Question

I have list array object like:

let arr = [
    { a: 1, b: 2, c: 3, d: 4 },
    { a: 2, b: 3, c: 4, d: 5 },
    { a: 5, b: 6, c: 7, d: 8 }
]

and after using reduce()

// get props **b, c**
let arr_result = arr.reduce( ... )

// arr_result = [
//    { b: 2, c: 3 },
//    { b: 3, c: 4 },
//    { b: 6, c: 7 }
// ]

Answer 1

use map .

 let arr = [{ a: 1, b: 2, c: 3, d: 4 }, { a: 2, b: 3, c: 4, d: 5 }, { a: 5, b: 6, c: 7, d: 8 } ] const output = arr.map(({b, c}) => ({b, c})); console.log(output);

Answer 2

You can use ES6(and beyond)'s object destructuring .

 const arr = [ { a: 1, b: 2, c: 3, d: 4 }, { a: 2, b: 3, c: 4, d: 5 }, { a: 5, b: 6, c: 7, d: 8 } ] const res = arr.map(obj => { const { b, c } = obj; return { b, c }; }); console.log(res);

Answer 3

Since you asked to achieve this using reduce, here is the way. Pass an empty array as thisArg & inside reduce callback function create an object with required key and push it to the accumulator

 let arr = [{ a: 1, b: 2, c: 3, d: 4 }, { a: 2, b: 3, c: 4, d: 5 }, { a: 5, b: 6, c: 7, d: 8 } ]; let newArr = arr.reduce(function(acc, curr) { acc.push({ b: curr.b, c: curr.c }) return acc; }, []) console.log(newArr)

Answer 4

If you want to use reduce :

 const arr = [{a:1,b:2,c:3,d:4},{a:2,b:3,c:4,d:5},{a:5,b:6,c:7,d:8}]; const res = arr.reduce((a, { b, c }) => (a.push({ b, c }), a), []); console.log(res);

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It's honestly a lot easier with map :

 const arr = [{a:1,b:2,c:3,d:4},{a:2,b:3,c:4,d:5},{a:5,b:6,c:7,d:8}]; const res = arr.map(({ b, c }) => ({ b, c })); console.log(res);

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