FUNCTIONS AS VALUES

Because function names in ECMAScript are nothing more than variables, functions can be used anywhere variables can be used. This means it's possible not only to pass a function into another function as an argument, but also to return a function as the result of another function. Consider the following function:

function callSomeFunction(someFunction, someArgument) {
 return someFunction(someArgument);
}

This function accepts two arguments. The first argument should be a function, and the second argument should be a value to pass to that function. Any function can then be passed in as follows:

function add10(num) {
 return num + 10;
}
          
let result1 = callSomeFunction(add10, 10);
console.log(result1); // 20
          
function getGreeting(name) {
 return "Hello, " + name;
}
          
let result2 = callSomeFunction(getGreeting, "Nicholas");
console.log(result2);  // "Hello, Nicholas"

The callSomeFunction() function is generic...