Find object value in array of objects JavaScript

Question

I want to check if a object value exist in a array of objects with "some".

I only can find that the object hobbys exist in the array with "some"

"users": [ { "type": "User", "name": "Sarah", "hobbys": { first: "something1", second: "something2" } } ] users.some(item => item.hobbys); // true

I want to check if "first" value in "hobbys" exist.

@DennisVash That will throw if user.hobbies does not exist — CertainPerformance, CommentedMay 10, 2019 at 9:22
@CertainPerformance users.some(user => user.hobbies && user.hobbies.first); ;-) — Dennis Vash, CommentedMay 10, 2019 at 9:25

CertainPerformance · Accepted Answer · 2019-05-10 09:08:58Z

1

Check if the hobbys is an object and has an own property of first:

const users = [{ "type": "User", "name": "Sarah", "hobbys": { first: "something1", second: "something2" } }]; const userWithFirstHobbyExists = users.some(({ hobbys }) => ( typeof hobbys === 'object' && hobbys.hasOwnProperty('first') )); console.log(userWithFirstHobbyExists);

answered May 10, 2019 at 9:08

CertainPerformance

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To me hasOwnProperty() is a tool for tracking down the inheritance, which is muuuuch slower than simple users.some(item => item.hobbys.first != undefined || false). What's the benefit of using hasOwnProperty() here?
– Yevhen Horbunkov
CommentedMay 10, 2019 at 9:16
hasOwnProperty is the way to check to see if the property exists on the object: != undefined will also evaluate to false if the property does exist, but its value is undefined. It's an edge case, but from OP's question, it's not clear if it's something to worry about or not. If he also wants to exclude first values of undefined, then you're right, check !== undefined
– CertainPerformance
CommentedMay 10, 2019 at 9:19
1
The question body states "want to check if "first" value in "hobbys" exist", so regardless of the first value, hasOwnProperty() seems to be massive overkill.
– Yevhen Horbunkov
CommentedMay 10, 2019 at 9:21

Add a comment |

Nikhil Aggarwal · Accepted Answer · 2019-05-10 09:12:50Z

You can try following assuming hobbys will always be an object and first will not have any falsy values.

let users = [{"type": "User","name": "Sarah","hobbys": {"first": "something1","second": "something2"}}]; console.log(users.some(item => item.hobbys && item.hobbys.first)); // true

Kaushik · Accepted Answer · 2019-05-10 09:11:14Z

You can use "key" in obj also to check if a key is part if object.

const users = [{ "type": "User", "name": "Sarah", "hobbys": { first: "something1", second: "something2" } }]; const userWithFirstHobbyExists = users.some(({ hobbys }) => ( typeof hobbys === 'object' && ('first' in hobbys ) )); console.log(userWithFirstHobbyExists);

Alternate and fast way to check is

 const users = [{ "type": "User", "name": "Sarah", "hobbys": { first: "something1", second: "something2" } }]; const userWithFirstHobbyExists = users.some(({ hobbys }) => ( typeof hobbys === 'object' && hobbys['first'] !== undefined )); console.log(userWithFirstHobbyExists);

Manikandan Velayutham · Accepted Answer · 2019-05-10 09:20:02Z

const users = [{ "type": "User", "name": "Sarah", "hobbys": { first: "somethig1", second: "something2" } }]; const hobbyExists = users.some(({ hobbys }) => (typeof hobbys === 'object' && hobbys['first'])); console.log(hobbyExists);

Badri Chorapalli · Accepted Answer · 2019-05-10 09:35:35Z

function will return true if it has value else false

let jData = { "users": [{ "type": "User", "name": "Sarah", "hobbys": { "first": "something1", "second": "something2" } }] }; function hasValue(data, obj, key) { return data.some(item => item[obj] && item[obj][key]); } console.log(hasValue(jData.users, 'hobbys', 'second')) //true console.log(hasValue(jData.users, 'hobbys', 'first')) // true console.log(hasValue(jData.users, 'test', 'first')) //false

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