Question

What's the output?

const name = 'Lydia';
age = 21;

console.log(delete name);
console.log(delete age);

• A: false, true
• B: "Lydia", 21
• C: true, true
• D: undefined, undefined

Answer 1

Answer: A

The delete operator returns a boolean value: true on a successful deletion, else it'll return false. However, variables declared with the var, const or let keyword cannot be deleted using the delete operator.

The name variable was declared with a const keyword, so its deletion is not successful: false is returned. When we set age equal to 21, we actually added a property called age to the global object. You can successfully delete properties from objects this way, also the global object, so delete age returns true.