slide môn học HDJ bài 7 the foundation of javascript syntax

 JavaScript is a scripting language developed by Sun Microsystems and Netscape.. JavaScript effects and rules ► JavaScript can enhance the dynamics and interactivity of the site by usin

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The Foundation of JavaScript Syntax

Session 7

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 Describe JavaScript

 Understand foundation of JavaScript syntax

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 JavaScript JavaScript makes makes it it easier easier to to create create

dynamic and interactive Web pages.

 JavaScript is a scripting language developed by Sun Microsystems and Netscape.

 JavaScript developed from Netscape's Livescript.

 Where is JavaScript running ?

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JavaScript effects and rules

► JavaScript can enhance the dynamics and interactivity of the site by using its effects.

 Provide User Interaction

 Dynamically Change Content

 Validate data

 Provide Database Interaction

► Similar to any other language, JavaScript also follows some basic grammar rules like:

 Using Caps JavaScript is case sensitive

 Using Pairs Open and closed symbols need to work in pairs

 Using Spaces JavaScript ignores extra white space

 Using Comments make notes to yourself about what the script

is doing

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JavaScript Tools and Run- Time

Environment

►The JavaScript code-generating tools and IDE helps in creating useful JavaScript code A few of these include:

►Run Time Environment

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Client-Side JavaScript

►If a client-side script is embedded in the page, the server forwards the full content of the HTML document – The JavaScript statements and the HTML content

►When the browser receives the document, it executes the HTML and JavaScript statements without any interaction with the server

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Server-Side JavaScript

►We can embedded JavaScript statements in

an HTML document that are executed on the server

executable in bytecode format

executable, the run-time engine executes the server-side JavaScript statements and returns the HTML page to the browser

►Some of the uses of server-side scripts

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Embedding JavaScript in Web Page

document in the following ways :

 Using SCRIPT tag:

JavaScript statements;

// >

</script>

 Using an external File

 Using JavaScript Expressions within HTML Tag

Attribute Values

 Using JavaScript in event handlers

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Program Using Msg box and write

method

Example:

<HTML>

<HEAD>

confirm ("Are you Sure?");

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they are declared in the script

 Global Variable

 Local Variable

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Data Type - Example

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Literal - Types

hexadecimal and binary number system.

point or an “e” or “”E” followed by an integer.

enclosed in single or double quotation marks.

False.

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(operands) and return a new value

they perform like:

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Arithmetic Operator

(either literals or variables) as their operands and return a single numerical value

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Comparison Operator

and returns a logical value based on whether the comparison is true or not

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Logical Operators

multiple comparisons into a conditional

expression

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Logical Operators - Example

alert ("The value of x is "

+ x + "The value of y is " + y);

alert("x AND y = " + (x && y));

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String Operator

operands and creates a new string, which is same, as the two original strings run together

Example:

x = ‘yellow’;

y = ‘green’;

z = x + y + ‘white’;

which means z is “yellowgreenwhite”

w = y + 9, which means w is “green9”

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Evaluation Operator

 Conditional operator

condition) ? trueVal : falseVal

Assigns a specified value to a variable if a condition is

true, otherwise assigns an alternate value if condition

is false

eg.

status = (age >= 18) ? "adult" : "minor“

 Typeof operator

The typeof operator returns a string indicating the

type of the operand.

eg

var x = 5;

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Operator Precedence

► When there are several operators to be evaluated in

an expression, the precedence of the operator determines the sequence in which the operators are evaluated

► The following table lists the precedence of

operators, from lowest to highest:

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variables in different contexts

and operators which evaluates to a single value

 Arithmetic: evaluates to a number

 Logical: evaluates to a boolean value

 String: evaluates to a string

together via operators

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Regular Expression

be used to match the character combinations of a string

character patters in a string input by the user

 Simple patterns

 Combination of simple and special characters

ways:

 Using an object initializer

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Using Regular Expression

Expression includes:

 Exec, Test, Match, Search, Replace, Split

of the object is:

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Regular Expression - Example

str = re.test ("Time and Tide

wait for none");

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the same name

value

arrayObjectName = new Array([element0, element1, ,

elementN])

we create it Eg emp[0] = "Ryan Dias"

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manipulate the array

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Conditional Statements

► A conditional statement is used to test a

condition The result determines the statement or block of statements to be executed.

► The various conditional statements include:

 If… Else

 Switch

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► JavaScript has several pre-defined functions that

we can use within the script.

► Some of pre-defined JavaScript functions

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