Functions that operate on other functions, either by taking them as arguments or by returning them, are called higher-order functions.
Higher order functions are a result of functions being first-class citizens in javascript.
Examples of higher order functions:
function higherOrder(fn) {
fn();
}
higherOrder(function() { console.log("Hello world") });
function higherOrder2() {
return function() {
return "Do something";
}
}
var x = higherOrder2();
x() // Returns "Do something"
