I have two array of objects, in which if id and aid property values match then append the property code to arr1 and return the result

var arr1 = [
  { id: 1, name: "xxx", cn: "IN" },
  { id: 2, name: "yyy", cn: "MY" },
  { id: 3, name: "zzz", cn: "SG" },
]

var arr2 = [
  { aid: 1, code: "finance" },
  { aid: 2, code: "others" },
  { aid: 4, code: "finance" },
  { aid: 5, code: "product" },
]

Expected result:

var arr1 = [
  { id: 1, name: "xxx", cn: "IN", code: 'finance'},
  { id: 2, name: "yyy", cn: "MY", code: 'others'},
  { id: 3, name: "zzz", cn: "SG", code: ''},
]

I tried

var result = arr1.map(e=> ({
  ...e,
  code: arr2.map(i=>i.code)
})

CodePudding user response：

You can do what you require with a loop over arr1 looking for matches in arr2 using filter(). This will add the code property to the existing arr1 array without creating a new array instance.

Note that this logic assumes that there will only ever be 0 or 1 matches in arr2.

var arr1 = [
  { id: 1, name: "xxx", cn: "IN" },
  { id: 2, name: "yyy", cn: "MY" },
  { id: 3, name: "zzz", cn: "SG" },
]

var arr2 = [
  { aid: 1, code: "finance" },
  { aid: 2, code: "others" },
  { aid: 4, code: "finance" },
  { aid: 5, code: "product" },
]

arr1.forEach(o1 => o1.code = arr2.filter(o2 => o2.aid === o1.id)[0]?.code || ''); 
console.log(arr1);

CodePudding user response：

I am not sure if this is the most optimal solution but this definitely works for your case:

let result = arr1.map((outerObj) => {
    // First we try to find the index of the matching object
    let index = arr2.findIndex((innerObj) => {
        return outerObj.id == innerObj.aid;
    });

    // In case of no match, set case as "" as per requirement
    if(index == -1) {
        outerObj.code = "";
        return outerObj;
    }

    // If a match is found, then combine the two objects.
    let mergedObj = { ...outerObj, ...arr2[index]}; 

    // aid is not needed in the result, Who wants aids anyway? 
    delete mergedObj.aid;
    return mergedObj;
});

If not more optimal, then definitely there could be smaller code but I think the code should be clear and readable rather than being smaller.

CodePudding user response：

First, massage the data into a format for fast manipulation; then manipulate.

The following:

1. Puts every item in arr2 into a map, keyed on aid
2. Enumerates arr1 once, looking into the map for each item to see if there is a corresponding code

Performance: O(N).

var arr1= [
  {id:1, name: "xxx", cn: "IN"},
  {id:2, name: "yyy", cn: "MY"},
  {id:3, name: "zzz", cn: "SG"} ]

var arr2 = [
  { aid: 1, code: "finance"},
  { aid: 2, code: "others"},
  { aid: 4, code: "finance"},
  { aid: 5, code: "product"} ]

const map = arr2.reduce((p,c) => p.set(c.aid, c), new Map)

arr1.forEach((i) => i.code = map.get(i.id)?.code || '')

console.log(arr1)

CodePudding user response：

You need to first find matching item in arr2 and them create the composed item.

Try like this:

var arr1 = [
  { id: 1, name: "xxx", cn: "IN" },
  { id: 2, name: "yyy", cn: "MY" },
  { id: 3, name: "zzz", cn: "SG" },
];

var arr2 = [
  { aid: 1, code: "finance" },
  { aid: 2, code: "others" },
  { aid: 4, code: "finance" },
  { aid: 5, code: "product" },
];

const result = arr1.map((item) => {
  const match = arr2.find((o) => o.aid === item.id);
  return { ...item, code: match ? match.code : '' };
});

console.log(result);

CodePudding user response：

we can get like this too

var arr1 = [
  { id: 1, name: "xxx", cn: "IN" },
  { id: 2, name: "yyy", cn: "MY" },
  { id: 3, name: "zzz", cn: "SG" },
]

var arr2 = [
  { aid: 1, code: "finance" },
  { aid: 2, code: "others" },
  { aid: 4, code: "finance" },
  { aid: 5, code: "product" },
]

const fun = (ar, ar2)=>{
const getResult = ar.map((e)=> {
  const Data ={
    id : e.id,
    name : e.name,
    cn : e.cn,
    code : ar2.find((e2)=> e2.aid===e.id)?.code || ""
}
    return Data;
})
return getResult
}
console.log(fun(arr1, arr2))

CodePudding user response：

we can usefind method too

var arr1 = [
  { id: 1, name: "xxx", cn: "IN" },
  { id: 2, name: "yyy", cn: "MY" },
  { id: 3, name: "zzz", cn: "SG" },
]

var arr2 = [
  { aid: 1, code: "finance" },
  { aid: 2, code: "others" },
  { aid: 4, code: "finance" },
  { aid: 5, code: "product" },
]

arr1.forEach(e => e.code = arr2.find(d => d.aid === e.id)?.code || ''); 
console.log(arr1);