Function Expression:
- A function defined within an expression, often assigned to a variable. Unlike function declarations, function expressions are not hoisted and must be defined before they are invoked.
Arrow Function:
- A concise syntax for writing function expressions introduced in ES6. Arrow functions use the => syntax and have lexical this binding.
Implicit Return:
- A feature of arrow functions where a single expression is automatically returned without needing the return keyword or curly braces.
Lexical this:
- Arrow functions do not have their own this context. Instead, they inherit this from the surrounding lexical scope, ensuring consistent context within nested functions and callbacks.
Hoisting:
- JavaScript's behavior of moving function declarations to the top of their containing scope during the compile phase, allowing them to be invoked before their actual declaration in the code.
Anonymous Function:
- A function without a name, often used in function expressions and callbacks.
Block Body:
- The body of an arrow function enclosed in curly braces {}, allowing for multiple statements and the use of the return keyword.
Concise Body:
- The body of an arrow function without curly braces, suitable for single-expression functions that return a value implicitly.

Early JavaScript Development (1995): Functions could be defined as declarations or expressions, similar to other programming languages like C and Java. However, the syntax was more verbose, and handling of this was more complex.
Introduction of ES6 (2015): Arrow functions were introduced, providing a more concise syntax for writing function expressions. They also brought lexical this binding, simplifying the management of context within callbacks and nested functions.
Modern JavaScript Practices: Arrow functions have become a staple in modern JavaScript development, favored for their brevity and predictable this behavior. They are widely used in frameworks and libraries, enhancing code readability and maintainability.

Conciseness:
- Arrow functions reduce boilerplate code, making function definitions shorter and more readable, especially for simple operations.
Lexical this:
- Unlike traditional functions, arrow functions do not have their own this context. This feature helps avoid common pitfalls related to this in callbacks and event handlers.
No arguments Object:
- Arrow functions do not have their own arguments object. To access arguments, developers can use rest parameters instead.
Suitability for Functional Programming:
- Arrow functions are well-suited for functional programming paradigms, enabling the use of higher-order functions like map, filter, and reduce.
No new Keyword:
- Arrow functions cannot be used as constructor functions and will throw an error if used with the new keyword.

Day 13: Function Expressions and Arrow Functions