Function in javascript

What are Functions?

• Functions are reusable code blocks designed for particular tasks .
• Functions are executed when they are called or invoked .
• Functions are fundamental in all programming languages .

Program:*

function sayHello() {
console.log("Hello");
}
console.log("Hello")

Output:

Hello

Calling a Function

Calling a function means executing or running the function.

After creating a function, we can call it by using the function name followed by parentheses ().

Example

function greet() {
    console.log("Hello");
}

greet();

greet() is used to call the function. When the function is called, the code inside the function is executed.

Output:

Hello

Function Parameters

• Parameters allow us to send values to a function.
• Parameters are written inside parentheses () when we define a function.
• The values passed to the function are called arguments.

Example

function add(a, b) {
    console.log(a + b);
}

add(10, 5);

Output:

15

Function Return Values

• A function can return a value to the code that called it.
• The return statement is used to return a value from a function.
• The returned value can be stored in a variable or used in another operation.

Example

function add(a, b) {
    return a + b;
}

let result = add(10, 10);

console.log(result);

Output:

20

Here:

• return a + b → returns the result from the function.
• add(10, 5) → calls the function.
• result → stores the returned value.

Function Arguments

Function parameters and arguments are different.

• Parameters are the names written inside the parentheses when defining a function.
• Arguments are the actual values passed to the function when calling it.

Example

function add(a, b) {
    console.log(a * b);
}

add(10, 5);

Here:

• a and b → Parameters
• 10 and 5 → Arguments

Simple way to remember:

Parameter = Name
Argument = Value