Functions, Arrow Functions, and Callbacks
Refresh your understanding of functions, arrow functions, and callbacks.
Functions are instrumental in JavaScript programming and an essential concept for React development. Functions are blocks of reusable code that perform a specific task. They're necessary to write more concise and readable code, especially when creating React components.
JavaScript offers three primary types of functions:
Regular functions
Arrow functions
Callback (async) functions
Regular functions (standard functions)
In JavaScript, regular functions are declared using the function keyword. They can take parameters, perform operations, and return values.
console.log(greet("Alice")); // Hello, Alice!// Function declarationfunction greet(name) {return `Hello, ${name}!`;}// Function expression// An anonymous function assigned to a function expressionconst add = function(a, b) {return a + b;};console.log(add(2, 3)); // 5// Anonymous function (without a name)setTimeout(function() {console.log("This runs after 2 seconds");}, 2000);
Note:
Function declarations are hoisted, so they can be called before they are defined, e.g.,
greetfunction can be called before its definition.Function expressions ...