Answers for "check if array already contains object with a key"

javascript check if value exists in array of objects

var arr = [{ id: 1, name: 'JOHN' }, 
  { id: 2, name: 'JENNIE'}, 
  { id: 3, name: 'JENNAH' }];

function userExists(name) {
  return arr.some(function(el) {
    return el.name === name;
  }); 
}

console.log(userExists('JOHN')); // true
console.log(userExists('JUMBO')); // false

js find object that has key in array

myArray.find(x => x.id === '45').foo;