CODEWITHSUNDEEP
javascriptarraysreactjs
PandaMastr
PandaMastr

Reputation: 695

Extracting one value from array into a variable - ReactJS

I know that maybe i will sound stupid for some people , but i am trying to extract single value from my array and insert it into a variable . How was possible to do it . In my case i want to have a new variable with the value only of the fileId

const arrayOfFiles = rowData.files;

Output : 

[{…}, {…}]
0: {fileId: 166, fileExtension: "CSV"}
1: {fileId: 167, fileExtension: "XLSX"}
lastIndex: (...)
lastItem: (...)
length: 2
__proto__: Array(0)

Tryout

 arrayOfFiles.forEach(file=> console.log(file.fileId));

Output

166
167

But how can i insert this value into a single variable ? I gave a try something like this : 

const fileId = arrayOfFiles.forEach((file) => file.fileId);

But it returns me undefined . Any suggestions what am i doing wrong ?

Upvotes: 0

Views: 176

Answers (2)

pope_maverick
pope_maverick

Reputation: 980

the problem is with the forEach, unlike map, filter, reduce, find, etc.. it doesn't return any value, hence you're getting undefined.

const res = arrayOfFiles.forEach(file => file.fileId); // undefined

const res = arrayOfFiles.map(file => file.fileId); // [166, 167]

const res = arrayOfFiles.filter(file => file.fileId === 166); // [166]

const res = arrayOfFiles.find(file => file.fileId === 166); // 166

Upvotes: 0

Viral Rathod
Viral Rathod

Reputation: 91

const arrayOfFiles = [{fileId: 166, fileExtension: "CSV"}, {fileId: 167, fileExtension: "XLSX"}];
var ids = arrayOfFiles.map((file) => file.fileId);
console.log(ids)

Upvotes: 1

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