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COMPUTER SOFTWARE APPLICATION - CITS

• When explicitly called from JavaScript code.
• Automatically executed, such as in self-invoking functions.
Function Definition:
Before, using a user-defined function in JavaScript we have to create one. We can use the above syntax to
create a function in JavaScript. A function definition is sometimes also termed a function declaration or function
statement. Below are the rules for creating a function in JavaScript:
• Every function should begin with the keyword function followed by,

• A user-defined function name that should be unique,
• A list of parameters enclosed within parentheses and separated by commas,
• A list of statements composing the body of the function enclosed within curly braces {}.
Example 2: This example shows a basic declaration of a function in javascript.
• JavaScript
function calcAddition(number1, number2) {

return number1 + number2;
}
console.log(calcAddition(6,9));
Output

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In the above example, we have created a function named calcAddition,
• This function accepts two numbers as parameters and returns the addition of these two numbers.
• Accessing the function with just the function name without () will return the function object instead of the
function result.
There are three ways of writing a function in JavaScript:
Function Declaration:
It declares a function with a function keyword. The function declaration must have a function name.
Syntax:

function NSTI(paramA, paramB) {
// Set of statements
}
Function Expression:

It is similar to a function declaration without the function name. Function expressions can be stored in a variable
assignment.
Syntax:

let NSTI= function(paramA, paramB) {
// Set of statements
}
Example 3: This example explains the usage of the Function expression.
• Javascript
const square = function (number) {

return number * number;
};

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CITS : IT&ITES - Computer Software Application - Lesson 37 - 46