Függvénykifejezés

Függvénykifejezés is a Hungarian term that translates to "function expression" in English. It refers to a way of defining a function in programming languages where the function is treated as a value and can be assigned to a variable or passed as an argument to other functions. This is in contrast to a function declaration, which typically defines a function with a name at a particular scope.

In a function expression, the function is created at runtime. This allows for more dynamic behavior. For example, a function expression can be an anonymous function, meaning it doesn't have a name. It can also be immediately invoked, a pattern known as an Immediately Invoked Function Expression (IIFE), which is often used to create private scopes.

The syntax for a function expression varies slightly between programming languages. In JavaScript, for instance, it might look like this: const myFunction = function(parameters) { // function body }; Here, `myFunction` is a variable that holds the function value. This differs from a function declaration, which would be written as `function myFunction(parameters) { // function body };`. The key difference is that function declarations are often hoisted, meaning they can be called before they are defined in the code, while function expressions are not hoisted in the same way. Understanding function expressions is crucial for comprehending various programming paradigms and advanced language features.