Question

How can I define a function’s prototype in JavaScript? I want to do this like I would do it in C where you would do something like:

void myfunction(void);

void myfunction(void){
}

So is there any way to do this in JavaScript? I’m asking this because of the function declaration order that is required in JavaScript.

---

Edit:

I have an object:

function something(){
 var anArrayOfSomethingObjects;
 aPrivateFunction(){ 
    // does some stuff
    anArrayOfSomethingObjects[3].aPublicFunction();
 }

 return {
  functionA: function() { },
  aPublicFunction: function() { },
  functionC: function() { }
 }
}

privateFunction needs to access publicFunction which is declared afterwards.

How can I do this?

Answer 1

you have to really understand what is a dynamic language, and why your question doesn’t really make a lot of sense. your problem is not about ‘definition vs. declaration’ like on C, it’s most about statements order.

in JavaScript (as with most dynamic languages) a function definition like this

function whatever (params) {
   ...
}

is in fact syntactic sugar for an assignment statement like this:

whatever = function (params) {
   ...
}

as you can see, whatever is in fact a variable, and it’s assigned a function value. so you can’t call it before assigning it.

Of course, execution order doesn’t have to follow lexical order. If that’s your case, you just have to make sure you assign the needed variable before using it. If it’s a local variable and you want closure semantics, you can define it first and assign later, like this:

var myfunc = undefined;
function first () {
   ...
   myfunc (...);
   ...
}
myfunc = function (...) {
   ...
}