Check if object value exists within a Javascript array of objects and if not add a new object to array
I've assumed that ids are meant to be unique here. some is a great function for checking the existence of things in arrays:
const arr = [{ id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 3, username: 'ted' }];function add(arr, name) { const { length } = arr; const id = length + 1; const found = arr.some(el => el.username === name); if (!found) arr.push({ id, username: name }); return arr;}console.log(add(arr, 'ted'));
It's rather trivial to check for existing username:
var arr = [{ id: 1, username: 'fred' }, { id: 2, username: 'bill'}, { id: 3, username: 'ted' }];function userExists(username) { return arr.some(function(el) { return el.username === username; }); }console.log(userExists('fred')); // trueconsole.log(userExists('bred')); // falseBut it's not so obvious what to do when you have to add a new user to this array. The easiest way out - just pushing a new element with id equal to array.length + 1:
function addUser(username) { if (userExists(username)) { return false; } arr.push({ id: arr.length + 1, username: username }); return true;}addUser('fred'); // falseaddUser('bred'); // true, user `bred` addedIt will guarantee the IDs uniqueness, but will make this array look a bit strange if some elements will be taken off its end.
This small snippets works for me..
const arrayOfObject = [{ id: 1, name: 'john' }, {id: 2, name: 'max'}];const checkUsername = obj => obj.name === 'max';console.log(arrayOfObject.some(checkUsername))