How can I inner join with two object arrays in JavaScript?

Question

I need inner join with two array in javascript like this:

    
    array1 = 
    [
      {
        "id": 1,
        "name": "Tufan"
      },
      {
        "id": 2,
        "name": "Batuhan"
      },
      {
        "id": 3,
        "name": "Hasan"
      }
    ]
    
    array2 = 
    [
      {
        "name": "yyy",
        "externalid": "1",
        "value": "Asd"
      },
      {
        "name": "aaaa"
        "externalid": "2",
        "value": "ttt"
      }
    ]
    
    expectedArray = 
    [
      {
        "id": 1,
        "name": "Tufan",
        "externalid": "1",
        "value": "Asd"
      },
      {
        "id": 2,
        "name": "Batuhan",
        "externalid": "2",
        "value": "ttt"
      }
    ]

rules:

on: array2.externalid = array1.id
select: array1.id, array1.name, array2.externalid, array2.value

My approach:

array1.filter(e => array2.some(f => f.externalid == e.id));
// I need help for continue

How can I make this?

Doesn't matter information: I use ES5 and pure javascript

Maybe try this answer stackoverflow.com/questions/22593515/… , mix it with Object.assign() — Walter Stabosz
– Walter Stabosz, Commented Apr 27, 2022 at 13:33
Does this answer your question? Analog to SQL 'JOIN' for Javascript objects? — Mushroomator
– Mushroomator, Commented Apr 27, 2022 at 13:35

mgm793 · Accepted Answer · 2022-04-27 13:37:34Z

1

You can do it like this:

const res = array2.map((item) => {
  const related = array1.find((el) => el.id == item.externalid);
  return { ...item, ...related };
});

Using a map to loop over the array2 and a find to get the array1 relative.

answered Apr 27, 2022 at 13:37

mgm793

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2 Comments

Tufy Duck Over a year ago

... operator not supported es5 :(

Roko C. Buljan Over a year ago

@TufyDuck what browsers are your building this for? Why don't you use Babel if you're concerned?

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