How to replace data of an array if some value match

Question

I have this array's and I want to replace the data form the array1 with the data of array2 if there is some coincident, for example that replace from the array1 {"Dates":"05/25/2021","valor":"0"} the data of array2 {Dates: "05/25/2021", count: "20"} that match

array1 = [{Dates:"05/10/2021",count:"0"},{Dates:"05/11/2021",count:"0"},{Dates:"05/12/2021",count:"0"},{Dates:"05/13/2021",count:"0"},{Dates:"05/14/2021",count:"0"},{Dates:"05/15/2021",count:"0"},{Dates:"05/16/2021",count:"0"},{Dates:"05/17/2021",count:"0"},{Dates:"05/18/2021",count:"0"},{Dates:"05/19/2021",count:"0"},{Dates:"05/20/2021",count:"0"},{Dates:"05/21/2021",count:"0"},{Dates:"05/22/2021",count:"0"},{Dates:"05/23/2021",count:"0"},{Dates:"05/24/2021",count:"0"},{Dates:"05/25/2021",count:"0"},{Dates:"05/26/2021",count:"0"},{Dates:"05/27/2021",count:"0"},{Dates:"05/28/2021",count:"0"},{Dates:"05/29/2021",count:"0"},{Dates:"05/30/2021",count:"0"},{Dates:"05/31/2021",count:"0"},{Dates:"06/01/2021",count:"0"},{Dates:"06/02/2021",count:"0"},{Dates:"06/03/2021",count:"0"},{Dates:"06/04/2021",count:"0"},{Dates:"06/05/2021",count:"0"},{Dates:"06/06/2021",count:"0"},{Dates:"06/07/2021",count:"0"},{Dates:"06/08/2021",count:"0"}];

array2 = [{Dates: "05/25/2021", count: "20"},{Dates: "05/26/2021", count: "0"},{Dates: "05/27/2021", count: "3"},{Dates: "05/28/2021", count: "10"},{Dates: "06/07/2021", count: "0"}];

if someone can help me I will appreciate, thanks

score 0 · Answer 1 · answered Jun 08 '21 at 21:37

0

As a naive approach I would do it like this, is this what you are looking for ?

for(let i = 0; i < array1.length; i++) {
   for(let j = 0; j < array2.length; j++) {
      if(array1[i].Dates == array2[j].Dates)
         array1[i] = array2[j];
   }
}

answered Jun 08 '21 at 21:37

Clément Cartier

174
2
11

Yes, both answer help me a lot, thank you so much – Alexis Murillo Jun 08 '21 at 21:52

Liftoff · Accepted Answer · 2021-06-08T21:45:32.960

Using a combination of Array.find and Array.forEach, you can iterate through array2 and update the matching object in array1.

array2.forEach(elm => {
  let match = array1.find(x => {
    return x.Dates == elm.Dates
  });
  if(typeof(match) != "undefined")
    match.count = elm.count;
});

Full snippet:

array1 = [{"Dates":"05/10/2021",count:"0"},{"Dates":"05/11/2021",count:"0"},{"Dates":"05/12/2021",count:"0"},{"Dates":"05/13/2021",count:"0"},{"Dates":"05/14/2021",count:"0"},{"Dates":"05/15/2021",count:"0"},{"Dates":"05/16/2021",count:"0"},{"Dates":"05/17/2021",count:"0"},{"Dates":"05/18/2021",count:"0"},{"Dates":"05/19/2021",count:"0"},{"Dates":"05/20/2021",count:"0"},{"Dates":"05/21/2021",count:"0"},{"Dates":"05/22/2021",count:"0"},{"Dates":"05/23/2021",count:"0"},{"Dates":"05/24/2021",count:"0"},{"Dates":"05/25/2021",count:"0"},{"Dates":"05/26/2021",count:"0"},{"Dates":"05/27/2021",count:"0"},{"Dates":"05/28/2021",count:"0"},{"Dates":"05/29/2021",count:"0"},{"Dates":"05/30/2021",count:"0"},{"Dates":"05/31/2021",count:"0"},{"Dates":"06/01/2021",count:"0"},{"Dates":"06/02/2021",count:"0"},{"Dates":"06/03/2021",count:"0"},{"Dates":"06/04/2021",count:"0"},{"Dates":"06/05/2021",count:"0"},{"Dates":"06/06/2021",count:"0"},{"Dates":"06/07/2021",count:"0"},{"Dates":"06/08/2021",count:"0"}];

array2 = [{Dates: "05/25/2021", count: "20"},{Dates: "05/26/2021", count: "0"},{Dates: "05/27/2021", count: "3"},{Dates: "05/28/2021", count: "10"},{Dates: "06/07/2021", count: "0"}];

array2.forEach(elm => {
  let match = array1.find(x => {
    return x.Dates == elm.Dates
  });
  if(typeof(match) != "undefined")
    match.count = elm.count;
});

console.log(array1);

The `forEach` extension method would be more appropriate than `map` on `array2`. And I would recommend validating that `array1.find` returns value before setting the count property. It's not clear if `array2` dates are guaranteed to be in `array1`. — Hunter Web Apps, Jun 08 '21 at 21:41

score 0 · Answer 3 · answered Jun 08 '21 at 22:09

A way to only iterate each array once is to create a Map from array2 using Dates as keys , then map the first array using Object.assign().

If the get() in the assign method is undefined (no such date stored) it will just ignore the undefined and return the original values of array1 object.

This avoids all the additional array looping using methods like find() or nested for loops

const a2Map = new Map(array2.map(e => [e.Dates, e]))

const res = array1.map(e => Object.assign({}, e, a2Map.get(e.Dates)));

console.log(res);

<script>
array1 = [{"Dates":"05/10/2021",count:"0"},{"Dates":"05/11/2021",count:"0"},{"Dates":"05/12/2021",count:"0"},{"Dates":"05/13/2021",count:"0"},{"Dates":"05/14/2021",count:"0"},{"Dates":"05/15/2021",count:"0"},{"Dates":"05/16/2021",count:"0"},{"Dates":"05/17/2021",count:"0"},{"Dates":"05/18/2021",count:"0"},{"Dates":"05/19/2021",count:"0"},{"Dates":"05/20/2021",count:"0"},{"Dates":"05/21/2021",count:"0"},{"Dates":"05/22/2021",count:"0"},{"Dates":"05/23/2021",count:"0"},{"Dates":"05/24/2021",count:"0"},{"Dates":"05/25/2021",count:"0"},{"Dates":"05/26/2021",count:"0"},{"Dates":"05/27/2021",count:"0"},{"Dates":"05/28/2021",count:"0"},{"Dates":"05/29/2021",count:"0"},{"Dates":"05/30/2021",count:"0"},{"Dates":"05/31/2021",count:"0"},{"Dates":"06/01/2021",count:"0"},{"Dates":"06/02/2021",count:"0"},{"Dates":"06/03/2021",count:"0"},{"Dates":"06/04/2021",count:"0"},{"Dates":"06/05/2021",count:"0"},{"Dates":"06/06/2021",count:"0"},{"Dates":"06/07/2021",count:"0"},{"Dates":"06/08/2021",count:"0"}];

array2 = [{Dates: "05/25/2021", count: "20"},{Dates: "05/26/2021", count: "0"},{Dates: "05/27/2021", count: "3"},{Dates: "05/28/2021", count: "10"},{Dates: "06/07/2021", count: "0"}];

</script>

How to replace data of an array if some value match

3 Answers3