This is how we write and call a function in Javascript. You can copy paste this directly into the Javascript console:
function APPhelloWorld(Input){
return "Hello " + Input;
}
var Result = APPhelloWorld("World");
console.log(Result);
You should see something like this:
We can assign Javascript functions into variables like this:
var X = APPhelloWorld;
X("Fred");
Another thing we can do is make what is called a “closure”. This is a Javascript function which is able to bind to and reference an external variable on the fly. Like this:
var myEnclosedVariable = "Fred";
setTimeout(function(){
console.log("Call " + myEnclosedVariable);
}, 1000);
Under the hood Javascript is creating a closure which effectively is like creating an object on the fly which has the enclosed variable “myEnclosedVariable” as a member. The beauty of closures is they are a much more light weight way of creating an object that one would traditionally get in languages like C++. See how this runs in the console:
Closures are important in Javascript since it allows us to receive callbacks from core APIs in the browser like the setTimeout function.
Lua also has closures as a core part of the language.