根据与不同数组中 Object 的属性匹配的值，为数组中的每个 Object 添加属性

Question

I have two arrays of objects:

const arr1 = [ {key: '12', name: 'john'}, {key: '9', name: 'steve'}, {key: '4', name: 'harry'}, {key: '2', name: 'jane'} ];

const arr2 = [ {key: '12', age: '29', gender: 'm'}, {key: '9', age: '43', gender: 'm'}, {key: '4', age: '19', gender: 'm'}, {key: '2', age: '65', gender: 'f'} ];

arr1 will always contain the same amount of objects as arr2 , and the key property will always be consistent, eg in the above example keys '12', '9', '4', '2' are present in both arrays.

I'm looking for an efficient way to add the name property from each object in arr1 to the object in arr2 that has the same value for the key property. The above is a simplified example, in my use-case both arrays could potentially contain 300+ objects.

Expected outcome:

arr3 = [ {key: '12', age: '29', gender: 'm', name: 'john'}, {key: '9', age: '43', gender: 'm', name: 'steve'}, {key: '4', age: '19', gender: 'm', name: 'harry'}, {key: '2', age: '65', gender: 'f', name 'jane'} ];

I can achieve this with a nested loop that iterates over each object in arr1 and checks against each object in arr2 , but wondered if there was a simplified/more efficient way using some of the functions within the more recent versions of ECMAScript (which i'm still learning).

Answer 1

Assuming that arr1 and arr2 are always the same length and sorted by their keys you can do this:

let arr3=arr2;
for (let i = 0;i<arr1.length;i++){
    arr3[i].name=arr1[i].name;
}

my output from doing this:

[
  { key: '12', age: '29', gender: 'm', name: 'john' },
  { key: '9', age: '43', gender: 'm', name: 'steve' },
  { key: '4', age: '19', gender: 'm', name: 'harry' },
  { key: '2', age: '65', gender: 'f', name: 'jane' }
]

Answer 2

I hope this helps

 const arr1 = [ {key: '12', name: 'john'}, {key: '9', name: 'steve'}, {key: '4', name: 'harry'}, {key: '2', name: 'jane'} ]; const arr2 = [ {key: '12', age: '29', gender: 'm'}, {key: '9', age: '43', gender: 'm'}, {key: '4', age: '19', gender: 'm'}, {key: '2', age: '65', gender: 'f'} ]; const concat = arr1.concat(arr2); var arr3 = Object.values(concat.reduce((acc, {key, ...rest})=>{ acc[key] = {...(acc[key] || {}), ...{key, ...rest}}; return acc; },{})); console.log(arr3);

Answer 3

This will work.

 const arr1 = [ {key: '12', name: 'john'}, {key: '9', name: 'steve'}, {key: '4', name: 'harry'}, {key: '2', name: 'jane'} ]; const arr2 = [ {key: '12', age: '29', gender: 'm'}, {key: '9', age: '43', gender: 'm'}, {key: '4', age: '19', gender: 'm'}, {key: '2', age: '65', gender: 'f'} ]; arr2.map((elm, index) => { elm.name = arr1[index].name; }) console.log(arr2);

Answer 4

You can use Map to add name property

 const arr1 = [ {key: '12', name: 'john'}, {key: '9', name: 'steve'}, {key: '4', name: 'harry'}, {key: '2', name: 'jane'} ]; const arr2 = [ {key: '12', age: '29', gender: 'm'}, {key: '9', age: '43', gender: 'm'}, {key: '4', age: '19', gender: 'm'}, {key: '2', age: '65', gender: 'f'} ]; map=new Map() arr1.map(o=>map.set(o.key,o)) arr2.forEach(o=>o.name=map.get(o.key).name) console.log(arr2)

Answer 5

 const arr1 = [ {key: '12', name: 'john'}, {key: '9', name: 'steve'}, {key: '4', name: 'harry'}, {key: '2', name: 'jane'} ]; const arr2 = [ {key: '12', age: '29', gender: 'm'}, {key: '9', age: '43', gender: 'm'}, {key: '4', age: '19', gender: 'm'}, {key: '2', age: '65', gender: 'f'} ]; function merge(arr1, arr2) { return arr1.reduce((merged, currentObj)=>{ const index = merged.findIndex(ele =>currentObj.key === ele.key); index?== -1. merged[index] = {..,merged[index]. ..:currentObj}. merged;push(currentObj), return merged }.arr2) } console,log(merge(arr1,arr2))