DEV Community: Dharchini

JavaScript function

Dharchini — Wed, 16 Nov 2022 16:23:59 +0000

A JavaScript function is a section of code created to carry out a certain purpose. When "something" calls a JavaScript function, it is carried out (calls it).

Syntax of JavaScript Functions

A JavaScript function's definition consists of the function keyword, a name, and parentheses (). Function names may also include underscores, dollar signs, and other characters (same rules as variables). Names of parameters may be included in parenthesis and separated by commas:
(parameter1, parameter2, ...)

Curly brackets enclose the code that the function will execute: {}

The function definition lists the function arguments between parentheses (). When a function is called, values are sent to it as arguments.

The arguments (the parameters) operate as local variables within the function.

let x = myFunction(4, 3); // Function is called, return value will end up in x

function myFunction(a, b) {
return a * b; // Function returns the product of a and b
}

Declaration and Usage of Variables in JavaScript

Dharchini — Wed, 16 Nov 2022 15:52:55 +0000

In JavaScript, variables are specified using one of three syntaxes. By providing the grammar template for creating variables, I can illustrate them. A syntax template is a generalized form of a JavaScript component or phrase.

The rules for creating variables must be reviewed before we go on to the how-to.

Variables can start with a symbol, numeric, or underscore characters. A variable name should always start with an alphabetic letter in programming.

The variables may have additional alphabetic, numeric, or symbol characters after the first character. Making your variable names relevant is the secret to good variable naming, unless the variable is only used very briefly and insignificantly.

The three syntax templates for declaring new variables are:

let variable-name = expression;
var variable-name = expression;
const variable-name = expression;

What sets apart these three approaches to defining variables, you might wonder. Two of them are connected to the idea of "changing scope," The other version, which starts with const, will remain the same and can't be changed.

Introduction to JavaScript

Dharchini — Tue, 08 Nov 2022 19:10:50 +0000

Javascript is a dynamic computer programming language. It is lightweight and most commonly used as a part of web pages, whose implementations allow client-side script to interact with the user and make dynamic pages. It is an interpreted programming language with object-oriented capabilities.

Advantage

Less server interaction
Immediate feedback to the visitors
Increased interactivity
Richer interfaces

Data Types

JavaScript allows you to work with three primitive data types,

Numbers, eg. 123, 120.50 etc.
Strings of text e.g. "This text string" etc.
Boolean e.g. true or false

Variables

Variables are declared with the var keyword as follows. JavaScript is untyped language. This means that a JavaScript variable can hold a value of any data type.

 var name = "Ali";
 var money;
 money = 2000.50;

JavaScript Variable Scope
The scope of a variable is the region of your program in which it is defined. JavaScript variables have only two scopes.

Global Variables − A global variable has global scope which means it can be defined anywhere in your JavaScript code.

Local Variables − A local variable will be visible only within a function where it is defined. Function parameters are always local to that function.