javascript check if object with id exists in array code example

Example 1: how to check if an element exists in an array of objects js

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')); // true
console.log(userExists('bred')); // false

Example 2: check object in array javascript

var obj = {a: 5};
var array = [obj, "string", 5]; // Must be same object
array.indexOf(obj) !== -1 // True