What is a first class function

 A first-class function means that functions are treated like any other value in JavaScript. They can be:

• Assigned to a variable
• Passed as an argument to another function
• Returned from another function
• Stored in objects or arrays

Example

function greet() {
  return "Hello";
}

// Assigned to a variable
const sayHello = greet;

// Passed as an argument
function execute(fn) {
  console.log(fn());
}

execute(greet); // Hello

One-line Interview Answer

"In JavaScript, functions are first-class citizens, which means they can be assigned to variables, passed as arguments, returned from other functions, and stored in data structures like any other value."