Remove keys from object that are not in an array

Question

I'm looking for an elegant way to do the following:

I have a JS object:

     var sObject = {};
     sObject[Col1] = "Value1";
     sObject[Col2] = "Value2";
     sObject[Col2] = "Value3";

I also have an array

     var arrayCols=[];
     arrayCols.push("Col2");

What I am trying to do is remove all the key/values from sObject where Key != arrayCols key

Once the needful is done, my sObject should only contain Col2:Value2 as Col2 is the only key in the arrayCols

I'm trying something along the lines of:

var sObject = {};
sObject['Col1'] = "Value1";
sObject['Col2'] = "Value2";
sObject['Col2'] = "Value3";

var arrayCols = [];
arrayCols.push("Col2");

let newObject = {};

for (const [key, value] of Object.entries(sObject)) {
  if (key in arrayCols) {
    newObject[key] = value;
  }
}

console.log(newObject);

Note that I added quotes to your object key names in lines 2-4. — isherwood, Feb 09 '22 at 20:49
You can try to use filter - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter — Subir Kumar Sao, Feb 09 '22 at 20:50
Not really. There's no indication that those are variable values, and the array value implies that they were supposed to be strings. At any rate, I made it known so the question author could make corrections but the demo works without error. — isherwood, Feb 09 '22 at 21:01

score 2 · Accepted Answer · answered Feb 09 '22 at 20:50

2

You can use Object.fromEntries and map:

var obj = { Col1: "Value1",  Col2: "Value2",  Col3: "Value3" };
var cols = ["Col2"];

var result = Object.fromEntries(cols.map(col => [col, obj[col]]));

console.log(result);

answered Feb 09 '22 at 20:50

trincot

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Please add your answer to the duplicate question. – Heretic Monkey Feb 09 '22 at 20:54

Kosh · Answer 2 · 2022-02-09T20:58:16.637

1

E. g. using reduce:

var sObject = {};
sObject.Col1 = "Value1";
sObject.Col2 = "Value2";
sObject.Col2 = "Value3";

var arrayCols = [];
arrayCols.push("Col2");

sObject = arrayCols.reduce((a, k) => (a[k] = sObject[k], a), {})


console.log(sObject)

edited Feb 09 '22 at 20:58

answered Feb 09 '22 at 20:49

Kosh

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@trincot, you're right again =)) – Kosh Feb 09 '22 at 20:58

Remove keys from object that are not in an array

2 Answers2