program.js

// problem 05 every some
/*
Return a function that takes a list of valid users, and returns a function that returns true
if all of the supplied users exist in the original list of users.

You only need to check that the ids match.

## Example

    var goodUsers = [
      { id: 1 },
      { id: 2 },
      { id: 3 }
    ]

    // `checkUsersValid` is the function you'll define
    var testAllValid = checkUsersValid(goodUsers)

    testAllValid([
      { id: 2 },
      { id: 1 }
    ])
    // => true

    testAllValid([
      { id: 2 },
      { id: 4 },
      { id: 1 }
    ])
    // => false

## Arguments

  * goodUsers: a list of valid users

Use array#some and Array#every to check every user passed to your returned
function exists in the array passed to the exported function.

## Resources

  * https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/every
  * https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/some

## Boilerplate

    function checkUsersValid(goodUsers) {
      return function(submittedUsers) {
        // SOLUTION GOES HERE
      };
    }

    module.exports = checkUsersValid
    */
function isInUsers(users){
  return function(submittedUser) {
    return users.some(function(user){
      return user.id === submittedUser.id;
    });
  }
}
function checkUsersValid(goodUsers){
  return function(submittedUsers){
    return submittedUsers.every(isInUsers(goodUsers));
  };
}

module.exports = checkUsersValid;