This document provides an overview of JavaScript basics including variables, data types, operators, conditional statements, loops, functions, arrays, and error handling. It explains JavaScript syntax, how to include JavaScript code in HTML pages, and commonly used statements like if/else, switch case, while and for loops. It also covers JavaScript functions, returning values from functions, and printing pages. The document describes JavaScript strings and array objects, and their associated methods. Finally, it discusses different types of errors in JavaScript like syntax errors, runtime errors, and logical errors.
Introduction to JavaScript course. The course was updated in 2014-15.
Will allow you to understand what is JavaScript, what's it history and how you can use it.
The set of slides "Introduction to jQuery" is a follow up - which would allow the reader to have a basic understanding across JavaScript and jQuery.
Introduction to JavaScript course. The course was updated in 2014-15.
Will allow you to understand what is JavaScript, what's it history and how you can use it.
The set of slides "Introduction to jQuery" is a follow up - which would allow the reader to have a basic understanding across JavaScript and jQuery.
What is JavaScript?
JavaScript is a very powerful client-side scripting language. JavaScript is used mainly for enhancing the interaction of a user with the webpage. In other words, you can make your webpage more lively and interactive, with the help of JavaScript. JavaScript is also being used widely in game development and Mobile application development.
Things you should know about Javascript ES5. A programming language that enables you to create dynamically updating content, control multimedia, animate images, and pretty much everything else
JavaScript Arithmetic Operators
Arithmetic operators are used to perform arithmetic between variables and/or values.
JavaScript Assignment Operators
Assignment operators are used to assign values to JavaScript variables.
JavaScript String Operators
The + operator, and the += operator can also be used to concatenate (add) strings.
Comparison Operators
Comparison operators are used in logical statements to determine equality or difference between variables or values.
Conditional (Ternary) Operator
The conditional operator assigns a value to a variable based on a condition.
Logical Operators
Logical operators are used to determine the logic between variables or values.
JavaScript Bitwise Operators
Bit operators work on 32 bits numbers. Any numeric operand in the operation is converted into a 32 bit number. The result is converted back to a JavaScript number.
The delete Operator
The delete operator deletes a property from an object:
In JavaScript, almost "everything" is an object.
-Booleans can be objects (if defined with the new keyword)
-Numbers can be objects (if defined with the new keyword)
-Strings can be objects (if defined with the new keyword)
-Dates are always objects
-Maths are always objects
-Regular expressions are always objects
-Arrays are always objects
-Functions are always objects
-Objects are always objects
What is the DOM?
The DOM is a W3C (World Wide Web Consortium) standard.
The DOM defines a standard for accessing documents:
"The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document."
The W3C DOM standard is separated into 3 different parts:
Core DOM - standard model for all document types
XML DOM - standard model for XML documents
HTML DOM - standard model for HTML documents
The HTML DOM (Document Object Model)
When a web page is loaded, the browser creates a Document Object Model of the page.
The HTML DOM model is constructed as a tree of Objects.
With the HTML DOM, JavaScript can access and change all the elements of an HTML document.
What is JavaScript?
JavaScript is a very powerful client-side scripting language. JavaScript is used mainly for enhancing the interaction of a user with the webpage. In other words, you can make your webpage more lively and interactive, with the help of JavaScript. JavaScript is also being used widely in game development and Mobile application development.
Things you should know about Javascript ES5. A programming language that enables you to create dynamically updating content, control multimedia, animate images, and pretty much everything else
JavaScript Arithmetic Operators
Arithmetic operators are used to perform arithmetic between variables and/or values.
JavaScript Assignment Operators
Assignment operators are used to assign values to JavaScript variables.
JavaScript String Operators
The + operator, and the += operator can also be used to concatenate (add) strings.
Comparison Operators
Comparison operators are used in logical statements to determine equality or difference between variables or values.
Conditional (Ternary) Operator
The conditional operator assigns a value to a variable based on a condition.
Logical Operators
Logical operators are used to determine the logic between variables or values.
JavaScript Bitwise Operators
Bit operators work on 32 bits numbers. Any numeric operand in the operation is converted into a 32 bit number. The result is converted back to a JavaScript number.
The delete Operator
The delete operator deletes a property from an object:
In JavaScript, almost "everything" is an object.
-Booleans can be objects (if defined with the new keyword)
-Numbers can be objects (if defined with the new keyword)
-Strings can be objects (if defined with the new keyword)
-Dates are always objects
-Maths are always objects
-Regular expressions are always objects
-Arrays are always objects
-Functions are always objects
-Objects are always objects
What is the DOM?
The DOM is a W3C (World Wide Web Consortium) standard.
The DOM defines a standard for accessing documents:
"The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document."
The W3C DOM standard is separated into 3 different parts:
Core DOM - standard model for all document types
XML DOM - standard model for XML documents
HTML DOM - standard model for HTML documents
The HTML DOM (Document Object Model)
When a web page is loaded, the browser creates a Document Object Model of the page.
The HTML DOM model is constructed as a tree of Objects.
With the HTML DOM, JavaScript can access and change all the elements of an HTML document.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
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The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
4. A program is a list of "instructions" to be "executed" by a computer.
JavaScript is used to create client-side dynamic pages.
JavaScript is an object-based scripting language which is lightweight and cross-platform.JavaScript is not a compiled
language, but it is a translated language.
The JavaScript Translator (embedded in the browser) is responsible for translating the JavaScript code for the web
browser.
The programming instructions are called statements.
5. JavaScript - Syntax
JavaScript can be implemented using JavaScript statements that are placed within the <script>... </script> HTML tags in a web page.
Place the <script> tags, containing your JavaScript, anywhere within your web page, but it is normally recommended that you should
keep it within the <head> tags.
The <script> tag alerts the browser program to start interpreting all the text between these tags as a script.
A simple syntax of your JavaScript will appear as follows.
<script ...> JavaScript code </script>
6. • The script tag takes two important attributes −
• Language − This attribute specifies what scripting language you are using. Typically, its value will
be javascript. Although recent versions of HTML (and XHTML, its successor) have phased out the
use of this attribute.
• Type − This attribute is what is now recommended to indicate the scripting language in use and its
value should be set to "text/javascript".
<script language = "javascript" type = "text/javascript">
JavaScript code
</script>
7. JavaScript in <body> and <head> Sections
• You can put your JavaScript code in <head> and <body> section altogether as follows −
<html>
<head>
<script type = "text/javascript">
function sayHello()
{ alert("Hello World") }
</script>
</head>
<body>
<script type = "text/javascript">
document.write("Hello World“)
</script>
<input type = "button" onclick = "sayHello()“ value = "Say Hello" />
</body>
</html>
8. STATEMENTS
JavaScript Statements
JavaScript statements are composed of: Values, Operators, Expressions, Keywords, and Comments.
The statements are executed, one by one, in the same order as they a
re written.
Semicolons separate JavaScript statements.
JavaScript White Space
JavaScript ignores multiple spaces. You can add white space to your script to
make it more readable.
The following lines are equivalent:
var person = “ANJU";
var person=“ANJU";
9. VARIABLES
EXAMPLES
var v1, v2, v3; // Declare 3 variables
v1= 5; // Assign the value 5 to v1
v2= 6; // Assign the value 6 to v2
v3 = a + b; // Assign the sum of v1and v2 to v3
a = 5; b = 6; c = a + b;
var sname= "Anju";
var sname="Anju";
Declaring or Creating JavaScript Variables
Creating a variable in JavaScript is called "declaring" a variable.
Declare a JavaScript variable with the var keyword:
var Studname;
To assign a value to the variable, use the equal sign:
studname = "Anju";
We can assign a valu to the variable when you declare it:
var Studname = “Anju”;
10. Operators,Expression,Keywords,Comments
JavaScript Keywor
ds
JavaScript keywords are used to identify
actions to be performed.
JavaScript Comme
nts
Code after double slashes // or between /* and */ is tre
ated as a comment.
Comments are ignored, and will not be executed:
Operators
Arithmetic Operators
Comparison Operators
Logical (or Relational) Operators
Assignment Operators
Conditional (or ternary) Operators
Expression
An expression is a combination of values, variables, and ope
rators, which computes to a value.
The computation is called an evaluation.
For example, 5 * 10 evaluates to 50
11. Operator Description Example
+ Addition 10+20 = 30
- Subtraction 20-10 = 10
* Multiplication 10*20 = 200
/ Division 20/10 = 2
% Modulus (Remainder) 20%10 = 0
++ Increment var a=10; a++; Now a = 11
-- Decrement var a=10; a--; Now a = 9
Arithmetic Operators
12. Operators Description
== Compares the equality of two
operands without considering
type.
=== Compares equality of two
operands with type.
!= Compares inequality of two
operands.
> Checks whether left side value is
greater than right side value. If
yes then returns true otherwise
false.
< Checks whether left operand is
less than right operand. If yes
then returns true otherwise
false.
>= Checks whether left operand is
greater than or equal to right
operand. If yes then returns true
otherwise false.
<= Checks whether left operand is
less than or equal to right
operand. If yes then returns true
otherwise false.
Comparison Operators
13. Operator Description
&& && is known as AND operator.
It checks whether two operands
are non-zero (0, false,
undefined, null or "" are
considered as zero), if yes then
returns 1 otherwise 0.
|| || is known as OR operator. It
checks whether any one of the
two operands is non-zero (0,
false, undefined, null or "" is
considered as zero).
! ! is known as NOT operator. It
reverses the boolean result of
the operand (or condition)
Logical Operators
14. Assignment operators Description
= Assigns right operand value to
left operand.
+= Sums up left and right operand
values and assign the result to
the left operand.
-= Subtract right operand value
from left operand value and
assign the result to the left
operand.
*= Multiply left and right operand
values and assign the result to
the left operand.
/= Divide left operand value by
right operand value and assign
the result to the left operand.
%= Get the modulus of left operand
Assignment Operators
15. Ternary Operator
JavaScript includes special operator called ternary operator :? that assigns a value to a variable based on some
condition. This is like short form of if-else condition.
Syntax:
<condition> ? <value1> :<value2>;
Example: Ternary operator
var a = 10, b = 5;
var c = a > b? a : b; // value of c would be 10
var d = a > b? b : a; // value of d would be 5
16. JAVASCRIPT IN EXTERNAL FILE
• The script tag provides a mechanism to allow you to
store JavaScript in an external file and then include it
into your HTML files.
<html>
<head>
<script type = "text/javascript" src = "filename.js" >
</script>
</head>
<body> ....... </body>
</html>
• the following content is saved in filename.js file and then you
can use sayHello function in your HTML file after including the
filename.js file.
function sayHello()
{ alert("Hello World"); }
17. CONDITIONAL STATEMENTS
For loop
if..else
statement.
switch
statement
The while Loop The do...while Loop
•To use conditional statements that allow your program to make correct
decisions and perform right actions.
• While writing a program, you may encounter a situation where you
need to perform an action over and over again. In such situations, you
would need to write loop statements to reduce the number of lines.
18. if...else Statement
.
• JavaScript supports conditional statements which
are used to perform different actions based on
different conditions. Here we will explain the
if..else statement. JavaScript supports the
following forms of if..else statement −
• if statement
• if...else statement
• if...else if... statement
Syntax
The syntax for a basic if statement is as follows −
if (expression)
{ Statement(s) to be executed if expression is true }
Syntax
if (expression)
{ Statement(s) to be executed if expression is true }
else
{ Statement(s) to be executed if expression is false }
Syntax
The syntax of an if-else-if statement is as follows −
if (expression 1)
{ Statement(s) to be executed if expression 1 is true }
else if (expression 2)
{ Statement(s) to be executed if expression 2 is true }
else if (expression 3)
{ Statement(s) to be executed if expression 3 is true }
else
{ Statement(s) to be executed if no expression is true }
19. JavaScript - Switch Case
Syntax
The objective of a switch statement is to give an expression to evaluate and several different statements to execute based on the
value of the expression. The interpreter checks each case against the value of the expression until a match is found. If nothing
matches, a default condition will be used.
switch (expression)
{ case condition 1:
statement(s)
break;
case condition 2:
statement(s)
break;
... case condition n:
statement(s)
break;
default: statement(s)
}
The break statements indicate the end of a particular case
20. JavaScript - While Loops
The purpose of a while loop is to execute a statement or code block repeatedly as long as an expression is true. Once the expression becomes false, the
loop terminates.
Syntax
The syntax of while loop in JavaScript is as follows −
while (expression)
{
Statement(s) to be executed if expression is true
}
<html>
<body>
<script type = "text/javascript">
var count = 0;
document.write("Starting Loop ");
while (count < 10)
{
document.write("Current Count : " + count + "<br />");
count++;
} document.write("Loop stopped!");
</script>
</body>
</html>
21. The do...while Loop
The do...while loop is similar to the while loop except that the condition check happens at the end of the
loop
PART 0
Syntax
The syntax for do-while loop in JavaScript is as follows −
do
{ Statement(s) to be executed; }
while (expression);
<html>
<body>
<script type = "text/javascript">
var count = 0;
document.write("Starting Loop" + "<br />");
do
{
document.write("Current Count : " + count + "<br />");
count++;
} while (count < 5);
document.write ("Loop stopped!");
</script>
</body>
</html>
22. JavaScript for loop
if you want to run the same code over and over again, each time with a different value.
Statement 1 is executed (one time) before the execution of the code block.
Statement 2 defines the condition for executing the code block.
Statement 3 is executed (every time) after the code block has been executed.
<html>
<body>
<script type = "text/javascript">
var count;
document.write("Starting Loop" + "<br />");
for(count = 0; count < 10; count++)
{ document.write("Current Count : " + count );
document.write("<br />");
}
document.write("Loop stopped!");
</script>
</body>
</html>
23. JavaScript - Loop Control
JavaScript provides break and continue statements. These statements are used to
immediately come out of any loop or to start the next iteration of any loop respectively.
.
The break statementStatement
The break statement, which was briefly introduced with the switch
statement, is used to exit a loop early, breaking out of the enclosing curly
braces.
<html>
<body>
<script type = "text/javascript">
var x = 1;
document.write("Entering the loop<br /> ");
while (x < 20)
{ if (x == 5)
break;
}
x = x + 1;
document.write( x + "<br />"); }
document.write("Exiting the loop!<br /> ");
</script>
</body>
</html>
The continue Statement
When a continue statement is encountered, the program
flow moves to the loop check expression immediately and
if the condition remains true, then it starts the next
iteration, otherwise the control comes out of the loop.
<html>
<body>
<script type = "text/javascript">
var x = 1;
document.write("Entering the loop<br /> ");
while (x < 10)
{ x = x + 1;
if (x == 5)
{
continue; // skip rest of the loop body }
document.write( x + "<br />"); }
document.write("Exiting the loop!<br /> ");
</script>
</body>
</html>
24. JAVASCRIPT - FUNCTIONS
Calling a Function
EXAMPLE
The most common way to define a function in JavaScript is by using the function keyword, followed by a unique
function name, a list of parameters (that might be empty), and a statement block surrounded by curly braces.
Syntax
<script type = "text/javascript">
function functionname(parameter-list)
{ statements }
</script>
<script type ="text/javascript">
function sayHello()
{alert("Hello there"); }
</script>
<html> <head>
<script type = "text/javascript">
function sayHello()
{ document.write ("Hello there!"); }
</script> </head>
<body>
<p>Click the following button to call the function</p>
<form> <input type = "button" onclick = "sayHello()" value = "Say Hello"> </form>
<p>Use different text in write method and then try...</p>
</body>
</html>
25. The return Statement
This is required to return a value from a function. This statement should be the last statement in a function.
<html>
<head>
<script type = "text/javascript">
function concatenate(first, last)
{
var full;
full = first + last;
return full;
}
function secondFunction()
{ var result;
result = concatenate(‘snehal', ‘smruti');
document.write (result );
}
</script>
</head>
<body>
<p>Click the following button to call the function</p>
<form>
<input type = "button" onclick = "secondFunction()" value = "Call Function">
</form>
</body>
</html>
26. JAVASCRIPT - PAGE PRINTING
The JavaScript print function window.print() prints the current web page when executed
PART 05
<html>
<head>
<script type="text/javascript">
</script>
</head>
<body>
<form>
<input type="button" value="Print" onclick="window.print()" />
</form>
</body>
<html>
27. JAVASCRIPT - THE STRINGS
OBJECT
The String parameter is a series of characters that has been properly encode
syntax to create a String object −
var val = new String(string);
Syntax
String Methods
Methods Explanation
length Returns the number of characters in a string
indexOf() Returns the index of the first time the specified
character occurs, or -1 if it never occurs, so
with that index you can determine if the string
contains the specified character.
lastIndexOf() Same as indexOf, only it starts from the right
and moves left.
match() Behaves similar to indexOf and lastIndexOf,
but the match method returns the specified
characters, or "null", instead of a numeric
value.
substr() Returns the characters you specified: (14,7)
returns 7 characters, from the 14th character.
substring() Returns the characters you specified: (7,14)
returns all characters between the 7th and the
14th.
toLowerCase() Converts a string to lower case
toUpperCase() Converts a string to upper case
29. It stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data
JAVASCRIPT - THE ARRAYS
OBJECT
JavaScript array is an object that represents a collection of similar type of elements.
There are 3 ways to construct array in JavaScript
By array literal
By creating instance of Array directly (using new keyword)
By using an Array constructor (using new keyword)
Syntax Creating an Array
Using an array literal is the easiest way to create a JavaScript Array.
var array_name = [item1, item2, ...];
var fruits = new Array( "apple", "orange", "mango" );
JavaScript Array directly (new keyword)
The syntax of creating array directly is given below:
var arrayname=new Array();
JavaScript array constructor (new keyword)
Here, you need to create instance of array by passing arguments in constructor so that we don't have to provide value
explicitly.
The example of creating object by array constructor is given below.
<script>
var emp=new Array("Jai","Vijay","Smith");
for (i=0;i<emp.length;i++){
document.write(emp[i] + "<br>");
}
</SCRIPT>
30. JavaScript - Errors & Exceptions Handling
Runtime Errors
Runtime errors, also called exceptions, occur during execution
There are three types of errors in programming: (a) Syntax Errors, (b) Runtime Errors, and (c) Logical Errors.
Syntax Errors
Syntax errors, also called parsing errors, occur at compile time in traditional programming languages and at interpret time in JavaScript.
Runtime Errors
Runtime errors, also called exceptions, occur during execution
Logical Errors
Logic errors can be the most difficult type of errors to track down. These errors are not the result of a syntax or runtime error. Instead, they occur when you make a
mistake in the logic that drives your script and you do not get the result you expected.
JavaScript implements the try...catch...finally construct as well as the throw operator to handle exceptions.
The try...catch...finally block syntax −
<script type = "text/javascript">
try
{ // Code to run [break;] }
catch ( e )
{ // Code to run if an exception occurs [break;] }
[ finally { // Code that is always executed regardless of // an exception occurring }]
</script>
31. <html>
<head>
<script type = "text/javascript">
function disp()
{ var a = 100;
alert("Value of variable a is : " + a );
} </script>
</head>
<body>
<p>Click the following to see the result:</p>
<form> <input type = "button" value = "Click Me" onclick = “disp();" />
</form>
</body>
</html>