PLAI - Acceleration Program for Generative A.I. Startups
Javascript
1.
2. Introduction
JavaScript is the most popular programming language in the
world.
JavaScript is the programming language of the Web.
Was designed to add interactivity to HTML pages.
All modern HTML pages are using JavaScript.
One of scripting language.
Supported by most the browsers
IE, Firefox, Chrome, Opera, Safari and Netscape Navigator.
3. Introduction
Embedded directly in HTML pages.
Java and JavaScript are two different languages.
Java can stand on its own.
JavaScript must be placed inside an HTML document to
function.
JavaScript is Case-sensitive.
4. Purpose
JavaScript Can Change HTML Content
JavaScript Can Change HTML Attributes
JavaScript Can Change HTML Styles (CSS)
JavaScript Can Validate Data
JavaScript Can display different pop-ups
5. Javascript in HTML
<script> tag is used to insert a JavaScript into an HTML
page.
Example:
<script>
document.getElementById("demo").innerHTML = "My First JavaScript";
</script>
Scripts in the body section
Scripts in the head section
Scripts in both the body section and head section
6. External JavaScript
External scripts are practical when the same code is used in
many different web pages.
External scripts cannot contain <script> tags.
Save it with a .js file extension.
“ xxx.js”
Call script "src" attribute, from any of your html pages
<script src="xxx.js">
Advantages:
It separates HTML and code.
It makes HTML and JavaScript easier to read and maintain.
Cached JavaScript files can speed up page loads.
7. JavaScript Output
Writing into an alert box, using window.alert().
<script> window.alert(5 + 6); </script>
Writing into the HTML output using document.write().
<script> document.write(5 + 6); </script>
Writing into an HTML element, using innerHTML.
<script>
document.getElementById("demo").innerHTML = 5+ 6;
</script>
Writing into the browser console, using console.log().
<script> console.log(5 + 6); </script>
8. JavaScript Comments
Single line comment: start the line with two slashes "//":
sum=a + b //calculating the sum
Multi line comment: "/*" and "*/"
/* This is a comment block. It contains several lines*/
9. JavaScript Variables
To store data values
Rules for Variable names:
Variable names are case sensitive
Names can contain letters, digits, underscores, and
dollar signs
They must begin with a letter ,the $ character or the
underscore character
JavaScript keywords cannot be used as names
Declaration: var x;
var name;
Assign value to variable: x=5;
name=“FTD” or ‘FTD’;
10. JavaScript Variables
Declare & Assign variables :
var x=5;
var name=“FTD” or ‘FTD’;
One Statement, Many Variables :
var x=5, name=“FTD” or ‘FTD’;
Local variables
Global variables
Lifetime of JavaScript local & global Variables
11. JavaScript Data Types
JavaScript variables can hold many data types.
String, Number, Boolean, Array, Object and more.
Used to be able to operate on variables.
Examples:
var length = 16; // Number
var lastName = "Johnson"; // String
var cars = [“Skoda", "Volvo", "BMW"]; // Array
var x = {firstName:"John", lastName:"Doe"}; // Object
var z= true; //Boolean
12. JavaScript Data Types
If the one operand is a string, JavaScript will also treat the
other operand as a string.
var x = 16 + "Volvo";
JavaScript evaluates expressions from left to right.
var x = 16 + 4 + "Volvo";
var x = "Volvo" + 16 + 4;
JavaScript has dynamic types. The same variable can be used
as different types
var x = 5; // Now x is a Number
var x = "John"; // Now x is a String
13. JavaScript Operators
Arithmetic +, -, *, /, %, --, ++
Assignment =, -=, +=,*=, /=
Logical &&, ||, !
Comparison ==, !=, >, <, <=, >=,
Ternary operator(a<b)?A=10:A=5
“===“equal value and equal type
“!==“not equal value or not equal type
above both compares both value and type, like below…
123=“123”
14. Functions
Function- is a block of code designed to perform a particular task and is
executed when
When an event occurs (when a user clicks a button)
When it is invoked (called) from JavaScript code
Automatically (self invoked)
Define the code once, and use it many times
Same code many times with different arguments, to produce different results.
Defining function
function function_name(arguments)
{
statements;
}
Return statement
return(“text”);
15. Conditional stmts
In JavaScript we have three conditional statements:
if statement
if...else statement
if …else if… else statement
Syntax:
if (condition1) {
block of code to be executed if condition1 is true
} else if (condition2) {
block of code to be executed if the condition1 is false and condition2 is true
} else {
block of code to be executed if the condition1 is false and condition2 is false
}
16. Switch stmts
Statement is used to perform different action based on different
conditions.
Syntax:
switch(expression) {
case n:
code n block
break;
case m:
code m block
break;
default:
default code block
}
17. Looping stmts
Loops can execute a block of code a number of times.
In JavaScript we have the following looping statements:
while
Syntax:
while (condition) {
code block to be executed
}
18. Looping stmts
do-while
Syntax:
do {
code block to be executed
}
while (condition);
for
Syntax:
for (statement 1; statement 2; statement 3) {
code block to be executed
}
19. Arrays
Arrays are used to store multiple values in a single variable.
Array creation :
1. var team=new Array();
team[0]=“FTD";
team[1]=“Mercury";
2. var team=new Array(“FTD",“Mercury");
3. var team=[“ftd",“Mercury“];
Access an Array: we can access array elements by using name of
the array and index value.
Array methods : length, sort and etc …
20. Events
Events are actions.
Examples of events:
1. A mouse click
2. Submitting an HTML form
3.A keystroke
<body> and <frameset> Events
Form Events
Image Events
Keyboard Events
Mouse Events
22. Popup Boxes
We can create three kinds of popup boxes:
Alert Box: information is displayed to the user.
Syntax: alert("sometext");
Confirm box: user to verify or accept something.
Syntax: confirm("sometext")
Prompt Box: user to input a value before entering a
page.
Syntax: prompt("sometext","defaultvalue")
23. Form validations
JavaScript can be used to validate input data in HTML
forms before sending off the content to a server.
verify Required Fields using JavaScript
verify Email using JavaScript
26. Assignments
Write a JavaScript program to get the website URL (loading
page)?
Write a JavaScript program to display the title of current page?
Write a JavaScript program to get the current date in
"dd/mm/yyyy" format?
Write a JavaScript program to find the area of a triangle where
lengths of the three of its sides are 5, 6, 7
Write a JavaScript program to calculate multiplication and
division of two numbers using functions(input from user).
27. Assignments
Assignment #1: Add field validations for HTML assignment #1 (Create an Employee Information Page)
The following fields should be mandatory, appropriate error message should display if the field is left blank or entered with
invalid data.
• Name field : Accept only alphabets and Max 20 characters.
• DOB (DD/MM/YYYY)
• What do you do Section
• Team Members text area
• Mailing Address
• Permanent Address
• Email ID field
Submit button : On clicking the ‘Submit’ button
• Display message: “Thank you. Your details are submitted successfully”, if valid data is entered in all the fields
• Display field level error message for each field, if invalid data is entered or filed is left blank.
Clear button: On clicking the ‘Clear’ button
• Entered data should be cleared for all the fields.
28. Assignment #2: Add field validations for HTML assignment #2 (Create a webpage as below with
your information)
The following fields should be mandatory, appropriate error message should display if the field is left blank or entered
with invalid data.
• Name: Accept only alphabets and Max 40 characters.
• Email: Accept alphabet, special characters & numbers, characters should present before and after @ symbol,
end with .com/.org/.in
• Gender ( radio button)
• County( Drop down list)
• Get back to me via: Email , Phone, Personally ( Check boxes)
• Comments: Text area of a fixed size.
Submit button : On clicking the ‘Submit’ button
• Display message: “Thank you. Your details are submitted successfully”, if valid data is entered in all the fields
• Display field level error message for each field, if invalid data is entered or filed is left blank.