17-check-if-an-object-has-a-property.js

/*
Check if an Object has a Property:
Finish writing the function so that it returns true if the object passed to it contains all four names, Alan, Jeff, Sarah
and Ryan and returns false otherwise.

- The users object should not be accessed directly
- The users object should only contain the keys Alan, Jeff, Sarah, and Ryan
- The function isEveryoneHere should return true if Alan, Jeff, Sarah, and Ryan are properties on the object passed to it.
- The function isEveryoneHere should return false if Alan is not a property on the object passed to it.
- The function isEveryoneHere should return false if Jeff is not a property on the object passed to it.
- The function isEveryoneHere should return false if Sarah is not a property on the object passed to it.
- The function isEveryoneHere should return false if Ryan is not a property on the object passed to it.
*/
let users = {
    Alan: {
        age: 27,
        online: true
    },
    Jeff: {
        age: 32,
        online: true
    },
    Sarah: {
        age: 48,
        online: true
    },
    Ryan: {
        age: 19,
        online: true
    }
};

function isEveryoneHere(userObj) {
    // Only changed code below this line
    return 'Alan' in userObj
        && 'Jeff' in userObj
        && 'Sarah' in userObj
        && 'Ryan' in userObj
    // Only changed code above this line
}

console.log(isEveryoneHere(users));