To achieve what you want, use JavaScript Closures. A closure is a function, which uses the scope in which it was declared when invoked. It is not the scope in which it was invoked.
Example
Let’s take your example and this is how you can achieve your task. Here, innerDisplay() is a JavaScript closure.
Var myFunction = (function () {
function display() {
// 5
};
function innerDisplay (a) {
if (/* some condition */ ) {
// 1
// 2
display();
}else {
// 3
// 4
display();
}
}
return innerDisplay;
})();