How to check object has existed or not in Array - Basic Javascript

Question

I have a basic problem with Javascript. This code is below.

var users = [{"user":{"id":1,"username":"google"}},{"user":{"id":2,"username":"yahoo"}}]
const result = users.filter(users.id === 1);
console.log(result);

I want to get result if user_id exist in array or not.

The error is:

false is not a function

• Elmer Dantas: Possible duplicate of How to determine if Javascript array contains an object with an attribute that equals a given value?

Answer 1

You need to take a callback, like an arrow function, with the right properties to the id, because you have a nested structure for every user.

var users = [{ user: { id: 1, username: "google" } }, { user: { id:2, username: "yahoo" } }];
const result = users.filter(user => user.user.id === 1);
console.log(result);

• KitKit: Thank you for your help!

Answer 2

You are writing the function in a wrong way

Try like this

const result = users.filter(x => x.user.id === 1);
console.log(result);

DEMO

• KitKit: Thank you for your help!

Answer 3

You need to pass a callback to the function. This will return you the items which id is 1.

const users = [{"user":{"id":1,"username":"google"}},{"user":{"id":2,"username":"yahoo"}}]
const result = users.filter(user => user.user.id === 1);
console.log(result);

Also instead of checking the length, you can use some function. This will terminate check of the rest items if any item was found.

const users = [{"user":{"id":1,"username":"google"}},{"user":{"id":2,"username":"yahoo"}}]
const result = users.some(user => user.user.id === 1);
console.log(result);

• KitKit: Thank you for your help!
• KitKit: This solution is best for me.!!

Answer 4

You might want to use reduce instead:

var users = [{"user":{"id":1,"username":"google"}},{"user":{"id":2,"username":"yahoo"}}]
const result = users.reduce((s, user) => s || user.user.id === 1, false);
console.log(result);

.filter returns an array, while .reduce can return whatever you want (in this case, a boolean).

If you want to use .filter, try:

var users = [{"user":{"id":1,"username":"google"}},{"user":{"id":2,"username":"yahoo"}}]
const result = !!users.filter(user => user.user.id === 1).length;
console.log(result);

However, keep in mind that .filter will create an extra array and might not be as efficient as .reduce.

• KitKit: Thank you for your help!
• KitKit: i will vote the best for your answer. Can you add solution with .filter return Boolean
• Derek 朕會功夫: @FeedGit Sure. Added.

Answer 5

Try like this

var users = [{"user":{"id":1,"username":"google"}},{"user":{"id":2,"username":"yahoo"}}]
const result = users[0].user.id;
console.log(result);

• KitKit: Thank you for your help!

Answer 6

var users = [{"user":{"id":1,"username":"google"}},{"user":
{"id":2,"username":"yahoo"}}]
const result = users.filter(function(el){
return (el.user.id===1)
});
console.log(result[0].user.username);
//This will print the username of the object with id==1 in array