Javascript Functions
What is Functions in JS:
JavaScript function is a fundamental building block in JavaScript programming.
What is JavaScript function?: is a block of code designed to perform a specific task.
Declaring Functions:
You can declare functions using the function keyword.
function functionName(parameters) {
// Code to be executed
}
Example:
function greet(name) {
console.log("Hello, " + name + "!");
}
// Call the function
greet("John"); // Output: Hello, John!
Runtime error: The name parameter was not provided, so greet function doesn't log a greeting.
Parameters:
Functions may have parameters, which simply serve for the values being passed to the function when it is called.
function add(a, b) {
return a + b;
}
let result = add(5, 3);
console.log(result); // Output: 8
Here, add is a function that takes two parameters (a and b) and returns their sum.
Return Statements:
The return statement is used to specify the value that a function should return.
function multiply(x, y) {
return x * y;
}
let product = multiply(4, 6);
console.log(product); // Output: 24
In this example, multiply returns the product of x and y.
Function Expressions:
Functions can also be assigned to variables, creating what is known as a function expression.
let sayHello = function(name) {
console.log("Hello, " + name + "!");
};
sayHello("Jane"); // Output: Hello, Jane!
In this example, sayHello is a function expression assigned to the variable sayHello.
Arrow Functions (ES6+):
Brief syntax of Arrow functions for representation of functions, which could be used for slight and simple operations (one-liners).
let square = (x) => x * x;
console.log(square(3)); // Output: 9
Here, square is an arrow function that takes a parameter x and returns its square.