In javascript function can be passed as argument or can be return value of function execution

first_class_function.js

//Function can be passed as argument
const sing = function(name) {
  return `${name} is singing a song`;
}

const letPerson = function(name,fn) {
  return fn(name);
}

letperson('Lorem',sing);

// Function can be return value
const myName = function(name) {
  return function() {
    return `My name is ${name}`;
  }
}

const whatsMyName = myName('Lorem') // this will return the function
whatsMyName();