függvénykifejezések

Függvénykifejezések, in English function expressions, are a fundamental concept in many programming languages, especially those that support first-class functions. A function expression is a way to define a function as part of a larger expression, rather than as a standalone declaration. This means that a function can be assigned to a variable, passed as an argument to another function, or returned as a value from a function.

Unlike function declarations, which are often hoisted to the top of their scope, function expressions are typically not hoisted. This means that a function expression cannot be called before it is defined. The syntax for a function expression usually involves the `function` keyword followed by an optional name, parameter list, and the function body enclosed in curly braces.

For example, in JavaScript, you might see `const greet = function(name) { return "Hello, " + name; };`. Here, `greet` is a variable that holds a function expression. This allows for dynamic creation and manipulation of functions. Anonymous function expressions, which lack a name, are very common and are often used for callbacks or immediately invoked function expressions (IIFEs).

The ability to treat functions as values opens up powerful programming paradigms like functional programming, enabling concepts such as higher-order functions, closures, and currying. Understanding function expressions is crucial for mastering more advanced programming techniques and writing flexible, modular code.