What are arrow functions?

Arrow functions are a concise syntax for writing functions in JavaScript, introduced in ES6 (ECMAScript 2015). They provide a shorter and often clearer way to define functions compared to traditional function expressions. **Syntax:** An arrow function uses the `=>` (arrow) token to separate the parameter list from the function body. For example: ```javascript // Traditional function expression const add = function(a, b) { return a + b; }; // Arrow function equivalent const add = (a, b) => a + b; ``` If the function has a single expression, you can omit the curly braces `{}` and the `return` keyword—this is called an implicit return. If the function body has multiple statements, you must use curly braces and explicitly return a value if needed: ```javascript const multiply = (a, b) => { const result = a * b; return result; }; ``` **Key Features and Use Cases:** 1. **Lexical `this` binding:** Unlike traditional functions, arrow functions do not have their own `this` context. Instead, they inherit `this` from the surrounding (lexical) scope. This makes them especially useful in scenarios like callbacks or methods where you want to preserve the outer `this` without using `.bind(this)`. 2. **Shorter syntax:** Arrow functions reduce boilerplate, making code more concise, especially for simple functions or inline callbacks such as array methods (`map`, `filter`, `reduce`). 3. **No `arguments` object:** Arrow functions do not have their own `arguments` object. If you need to access all arguments, you need to use rest parameters (`...args`) explicitly. 4. **Not suitable as constructors:** Arrow functions cannot be used as constructors and will throw an error if called with `new`. **Example use case:** ```javascript const numbers = [1, 2, 3, 4, 5]; const squares = numbers.map(n => n * n); console.log(squares); // [1, 4, 9, 16, 25] ``` In summary, arrow functions offer a compact syntax and are particularly useful when you want to write simple functions or need lexical `this` behavior, such as in event handlers or array operations. However, they are not a full replacement for all traditional functions, especially when you need function hoisting, `this` binding for methods, or constructors.