Conditional Statements : if, else, if else if, switch
Looping Statements : while, do..while, for, for..in
Part 3 (Coming Soon)
Functions
Arrays
Understanding the Scope : Availability of variables globally or locally
Part 4 (Coming Soon)
Understanding Objects Literals
Objects in JavaScripts : Number, Boolean, String, Date, Math
Understanding the DOM : Document Object Model
JavaScript Beginner’s Series : Part 1
JavaScript Overview
JavaScript is the assembly language of the Web. JavaScript is a high-level, dynamic, untyped, and interpreted programming language. Do not confuse JavaScript with Java.
In this beginner’s series, we’ll be learning the basic building blocks of JavaScript that every beginner or a newbie needs to know.
Ways to add JavaScript code on a HTML page
Adding JavaScript Code using the <script></script> tag with the type attribute
Adding JavaScript file using the src attribute of the <script></script> tag in the <head></head> section
JavaScript code or file is placed in the <head> section when you want to run some code on a click event somewhere on your web page.
Adding JavaScript code or file using the <script></script> tag in the <body></body> section
JavaScript code or file is placed in the <body> section when you want to generate some content on the web page using some JavaScript code as soon as the page loads.
Variables, DataTypes, Operators and Expressions
Variables
var keyword is used to declare a variable in JavaScript. You should always use the var keyword to declare a variable in JavaScript.
Types of variables in JavaScript :
Global variables (Global Scope)
Local and Block level variables (Local Scope)
Variables in JavaScript are written in CamelCase for ex: isItGlobal.
Let’s look at some code.
Data Types
Numbers : eg: 157, 457
Strings : eg: “This is string”, ‘This is string’
Booleans : eg: true or false
Undefined
In JavaScript, datatype is inferred by the type of data or value assigned for a variable.
For ex: If we assign 124 value to a variable var myValue = 124. The data type for myValue will be Number.
Let’s look at some code and find out the data type of a variable (using the typeof keyword).
Operators
Operators allows us to compute data in a programming language.
JavaScript support the following types of operators :
Arithmetic
Comparison
Logical
Assignment
Ternary
In order for an operator to work it needs two operands.
For ex:
4 + 5 = 9 Here, 4 and 5 are the two operands and + is the operator.
Arithmetic Operator
Comparison Operator
Logical Operator
Assignment Operator
The Assignment assigns values from the right side operand to the left side operand.
+= (Add & Assignment) : adds the right operand to the left operand and assigns the result to the left operand.
-= (Subtract & Assignment) : subtract the right operand to the left operand and assigns the result to the left operand.
*= (Multiple & Assignment) : Multiples the right operand to the left operand and assigns the result to the left operand.
/= (Division & Assignment) : Divides the right operand to the left operand and assigns the result to the left operand.
%= (Modulus & Assignment) : Modulus operation happens from right operand to left operand and assigns the result to the left operand.
Ternary Operator
The Ternary operator first checks the expressions for a true or false value and then executes the given statements.
For ex:
Part 2 coming soon
Thank you for reading.
Stay tuned!
Take care
Abhishek Luv
About author
.NET Online Instructor
Hello! My name is Abhishek Luv and I am an online trainer for C# & ASP.NET MVC from Mumbai, India. I provide my online training services in India and overseas. I have successfully done a lot of online training for clients from USA (Chicago, Pennsylvania, Texas, Oklahoma, Seattle, Florida, Michigan), Dubai, UK(Wales, London, Birmingham), Ireland(Dublin), Panama City, Colombia(Bogota), Denmark(Hjørring), Afghanistan, Switzerland(Zurich), Sri Lanka(Colombo), New Zealand, India(Hyderabad, Mumbai, Bangalore, Delhi, Faridabad, Kolkata, Chennai, Madurai, Gujarat).