javaScript Functions explained

Oh well, i made this topic because i've seen alot of codes here being misused.

So what is a function?

functions is a block of code that perform a routine or process. it can return a value or not return anything at all, just execute a block of code. It can also accept arguments or parameters. A function must not be duplicated in a document(which may contain more that 1 javascript). However it can be called many times.

Here's some example of the syntax, foo can be anything provided it doesnt begin with number and only contains letter and underscore.

function that execute a code

function foo() {
alert("hi");
}

how to call:

foo();

will show an alert with "hi" message

function that execute a code but requires a parameter

function foo(message) {
alert(message);
}

how to call:

foo("hi");

will show an alert with "hi" message

function returns a value

function foo() {
return "hi";
}

how to call:

alert(foo());

will show an alert with "hi" message

function returns a value but requires a parameter

function foo(message) {
if(message) return true;
return false;
}

how to call:

alert(foo("hi"));

will show an alert with "true" message


so now you know how to use a function. As I said a function must not be duplicated, it will cause bugs if you do.

Why use functions?
Basically we want our code short, in practicality we use function so that we can execute the same code many times without making the same code.