JavaScript Training in Ambala ! Batra Computer Centre

JAVASCRIPT TRAINING

IN AMBALA

Today We’ll Learn Javascript What is javascript Are Java & Javascript the Same? How to put javascript in an HTML page Ending statement with a Semicolon? Javascript Variables Operators in Javascript Popup Boxes in javascript

Ph. No. :9729666670,4000670 Website: www.batracomputercentre.com

JAVASCRIPTJavaScript is used in millions of Web pages to

improve the design, validate forms, detect browsers, create cookies, and much more.

JavaScript is the most popular scripting language on the internet, and works in all major browsers, such as Internet Explorer, Mozilla, Firefox, Netscape, Opera.


WHAT IS JAVASCRIPT JavaScript was designed to add interactivity to HTML

pages JavaScript is a scripting language (a scripting language is

a lightweight programming language) A JavaScript consists of lines of executable computer

code A JavaScript is usually embedded directly into HTML

pages JavaScript is an interpreted language (means that scripts

execute without preliminary compilation) Everyone can use JavaScript without purchasing a license


Are Java And Javascript The Same?

NO! Java and JavaScript are two completely

different languages in both concept and design!

Java (developed by Sun Microsystems) is a powerful and much more complex programming language - in the same category as C and C++.


How to put a javascrpit into an HTML page

<html><body><script type="text/javascript">document.write("Hello World!")</script></body></html>


Ending Statement with aSemicolon?

With traditional programming languages, like C++ and Java, each code statement has to end with a semicolon (;).

Many programmers continue this habit when writing JavaScript, but in general, semicolons are optional! However, semicolons are required if you want to put more than one statement on a single line.


Operators in

JavascriptThere are following important operators used in Javascripts:

Arithmetic Operator Assignment Operator Comparison Operator Logical Operator


Javascript Variables Variables are used to store data. A variable is a "container" for information you want

to store. A variable's value can change during the script. You can refer to a variable by name to see its value or to change its value.

Rules for variable names:• Variable names are case sensitive • They must begin with a letter or the underscore character

o strname – STRNAME (not same)


Arithmetic Operator Arithmetic operators are used to perform arithmetic

between variables and/or values. Given that y = 5, the table below explains the arithmetic

operators:– Addition– Subtraction– Multiplication– Division– Modulus– Increment– Decrement


Example


Assignment Operator

Assignment operators are used to assign values to JavaScript variables.

The basic assignment operator is equal (=), which assigns the value of its right operand to its left operand. That is, x = y assigns the value of y to x.

Given that x = 10 and y = 5, the table below explains the assignment operators:


Example


Comparison Operator Comparison operators are used in logical statements to

determine equality or difference between variables or values.

JavaScript has both strict and type–converting comparisons.

The more commonly-used abstract comparison (e.g. ==) converts the operands to the same type before making the comparison.

For relational abstract comparisons (e.g., <=), the operands are first converted to primitives, then to the same type, before comparison.


Example


Logical Operator

Logical operators are used to determine the logic between variables or values.

Logical operators are typically used with Boolean (logical) values.

However, the && and || operators actually return the value of one of the specified operands, so if these operators are used with non-Boolean values, they may return a non-Boolean value.


Example


Popup Boxes in Javascript

JavaScript has three kind of popup boxes: Alert box Confirm box Prompt box


Alert dailog Box

An alert dialog box is mostly used to give a warning message to the users. For example, if one input field requires to enter some text but the user does not provide any input, then as a part of validation, you can use an alert box to give a warning message.


Example


Output


After click on “Click Me” =>

Confirmation Dialog Box

A confirmation dialog box is mostly used to take user's consent on any option. It displays a dialog box with two buttons: Cancel.

If the user clicks on the OK button, the window method confirm() will return true. If the user clicks on the Cancel button, then confirm() returns false. You can use a confirmation dialog box as follows.


Example


Output



Prompt Dialog Box The prompt dialog box is very useful when you want to

pop-up a text box to get user input. Thus, it enables you to interact with the user. The user needs to fill in the field and then click OK.

This dialog box is displayed using a method called prompt() which takes two parameters: (i) a label which you want to display in the text box and (ii) a default string to display in the text box.

This dialog box has two buttons: OK and Cancel. If the user clicks the OK button, the window method prompt() will return the entered value from the text box.

If the user clicks the Cancel button, the window method prompt()returns null.


Example


Output




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SCO 15, Dayal Bagh, Near Hanuman Mandir, Ambala Cantt. Phn No.: 9729666670,0171-4000670 Email: [email protected] Website: www.batracomputercentre.com

JavaScript Training in Ambala ! Batra Computer Centre

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