Check for emptiness

importance: 5

Write the function isEmpty(obj) which returns true if the object has no properties, false otherwise.

Should work like that:

let schedule = {};
alert( isEmpty(schedule) ); // true
schedule["8:30"] = "get up";
alert( isEmpty(schedule) ); // false

Just loop over the object and return false immediately if there’s at least one property.

function isEmpty(obj) {
 for (let key in obj) {
 // if the loop has started, there is a property
 return false;
 }
 return true;
}