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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

Open a sandbox with tests.

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;

Open the solution with tests in a sandbox.