сохранение функции

js/script.js

function fun() {
document.write('Hello World!<br />');
}
//saving function in the variable
var val = fun();
//saving function in the array
var arra = [fun()];
//saving function in the object
var Obj = {
val: fun()
};
function funMake() {
val();
arra[0]();
Obj.val();
}

function fun() {
 document.write('Hello World!
');
}

//saving function in the variable
var val = fun();

//saving function in the array
var arra = [fun()];

//saving function in the object
var Obj = {
 val: fun()
};

function funMake() {
 val();
 arra[0]();
 Obj.val();
}

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<script src="js/script.js"></script>
</head>
<body>
<script>
funMake();
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<script src="js/script.js"></script>
</head>
<body>
<script>
funMake();
</script>
</body>
</html>