CODEWITHSUNDEEP
javascriptarrays
Stas Verevkin
Stas Verevkin

Reputation: 23

Need to mapped data between two arrays

Need some help to solve basic task.

I have two arrays of objects.

const firstArr = [
  {id: 1, action: 'pending'},
  {id: 2, action: 'pending'},
  {id: 3, action: 'pending'},
];

const secondArr = [
  {id: 1, action: 'accepted'},
  {id: 2, action: 'accepted'},
  {id: 3, action: 'accepted'},
  {id: 566, action: 'accepted'},
  {id: 333, action: 'accepted'},
  {id: 234, action: 'accepted'},
];

I need to find in second array all objects with equal ids from first array and change "action" property in second array on "action" property from first array

Upvotes: 0

Views: 49

Answers (3)

phi-rakib
phi-rakib

Reputation: 3302

You could use Map Object. Traverse the first array and set id as key and action as a value into Map Object. Then traverse the second array and look for id in the Map Object. If id is found then change the action.

const firstArr = [
  { id: 1, action: 'pending' },
  { id: 2, action: 'pending' },
  { id: 3, action: 'pending' },
];

const secondArr = [
  { id: 1, action: 'accepted' },
  { id: 2, action: 'accepted' },
  { id: 3, action: 'accepted' },
  { id: 566, action: 'accepted' },
  { id: 333, action: 'accepted' },
  { id: 234, action: 'accepted' },
];
const map = new Map();
firstArr.forEach(({ id, action }) => map.set(id, action));
const ret = secondArr.map((x) =>
  map.has(x.id) ? { ...x, action: map.get(x.id) } : { ...x }
);
console.log(ret);

Upvotes: 1

Nina Scholz
Nina Scholz

Reputation: 386578

You could gather all actions and map a new object with the wanted values.

const
    firstArr = [{ id: 1, action: 'pending' }, { id: 2, action: 'pending' }, { id: 3, action: 'pending' }],
    secondArr = [{ id: 1, action: 'accepted' }, { id: 2, action: 'accepted' }, { id: 3, action: 'accepted' }, { id: 566, action: 'accepted' }, { id: 333, action: 'accepted' }, { id: 234, action: 'accepted' }],
    states = Object.fromEntries(firstArr.map(({ id, action }) => [id, { action }])),
    result = secondArr.map(o => ({ ...o, ...states[o.id] }));

console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 0

codemonkey
codemonkey

Reputation: 7905

Here is one way to do that

const firstArr = [
  {id: 1, action: 'pending'},
  {id: 2, action: 'pending'},
  {id: 3, action: 'pending'},
];

const secondArr = [
  {id: 1, action: 'accepted'},
  {id: 2, action: 'accepted'},
  {id: 3, action: 'accepted'},
  {id: 566, action: 'accepted'},
  {id: 333, action: 'accepted'},
  {id: 234, action: 'accepted'},
];

secondArr.forEach((item, index) => {
  const fa = firstArr.find(i => i.id === item.id);
  if(fa)
    secondArr[index].action = fa.action
})
console.log(secondArr)

Loop through the second array, try to find a corresponding element in the first array and then, if found, grab its action and assign to to the proper index of the second array. Pretty basic, as you pointed out.

Upvotes: 0

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