HOF.js

function greet(name) {
    return `Hello, ${name}!`;
}

function shout(textFunction, name) {
    const text = textFunction(name);
    // toUpperCase is a built-in function of the
    // String object which returns the value of 
    // the string converted to uppercase (capital letters)
    const shoutText = text.toUpperCase();
    return shoutText;
} // here shout is a higher order function
// because it takes a function as an argument

var a = shout(greet, 'John');
console.log(a);

function greet(name) {
return Hello, ${name}!;
}

function greetV2(name) {
return Namaste, ${name}!;
}

function shout(textFunction, name) {
const text = textFunction(name);
// textFunction <<->> greet
// toUpperCase is a built-in function of the
// String object which returns the value of
return text;
} // here shout is a higher order function
// because it takes a function as an argument

var a = shout(greetV2, 'Suhail');
console.log(a);