08. session 08 intoduction to javascript
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This document introduces JavaScript and describes client-side and server-side usage. It explains that JavaScript is a scripting language used to build dynamic web pages and can run on the client-side in browsers or server-side. It also describes common data types in JavaScript, variables, functions, and keywords. Functions like toFixed(), toPrecision(), and toString() are presented as examples of built-in functions to format numbers and convert values to strings.
08. session 08 intoduction to javascript
- 1. Introduction to JavaScript Session 8
- 2. Explain Javasript language Describe client-side and server-side Javascript Describe build-in function Objectives
- 3. Javascript is a language that allows you build dynamic and interactive Web pages . Javascript is a scripting language developed by Sun Microsystems and Netscape. Javascript developed from Netscape’s Livescript Client application run in a broswer such as Netscape Navigator or Internet Explorer and Firefox Introduction
- 4. Sripting Scripting refers to a series of commands that are interpreted and executed sequentially and immediately on an occurrence of an event
- 5. Sripting Client side Scripting: Refer to a script being executed on the client’s machine by the browser. Server side Scripting: Refer to a script being executed on Web server to generate dynamic HTML pages .
- 6. <SCRIPT> Tag The <SCRIPT> tag defines a script for an HTML page to make them interactive There are two main purpose of the <SCRIPT> tag, which are: Identifies a given segment of script in the HTML page. Load an external script file .
- 7. Declaring Variable In Javascript, the var keyword is used to create a variable by allocating memory to it.
- 8. Rules Javascript is a case-sensitive language. These rules are that a variable name: Can consist of digit, underscore, and alphabets. Must begin with a letter or underscore character Cannot begin with a number and cannot contain any punctuation marks. Cannot contain any kind of special characters such as +,*,%,and so on. Cannot contain spaces Cannot be a Javascript keyword
- 9. Data Types
- 11. Composite Data Types A composite data type stores a collection of multiple related values, unlike primitive data types.
- 12. “ null “ Keyword The null keyword specifies that a variable does not hold any value. (the null value is not equal to zero because zero is a calculate value while null refers to the absence of a value)
- 13. Methods to display Javascript allows you to display information using the methods of the document object . The document object is a predefined object in Javascript write () : display any type of data writeln(): Display any type of data and appends a new line character.
- 14. Comments JavaScript support two types of comments. There are: Single - line comments Multi - line comments
- 15. Esccap Sequences Character There are multiple escape sequence characters in Javascript that provides various kind of formatting.
- 17. JavaScript Keywords Keywords are predefined terms that can not be used as an object name, function name or variable name JavaScript Keyword break case comment continue default delete do else export for function if import in Label new return switch this typeof var void while with
- 18. Build-in Functions Function Description Example toFixed Specifies the number of digits to be displayed after the decimal point var price = 23.456; var fixedprice = price.toFixed(2) return 23.46 toPrecision Specifies the number of digits to be displayed from a given number var price = 45.9431 alert(price. toPrecision(3)) return 45.9 toString Convert any value into a string value var age=25; alert(‘Age:’ + age.toString()+’years’) Return Age: 25 years
- 19. Summary The Javascript runtime engine reads and executes the Javascript code either on the server or in the browser. The Server element includes JavaScript code, which is executed by the Web Server. The NOSCRIPT element specifies the alternate content to be displayed, if the browser closes not support Javascript.
- 20. Summary… Javascript provides various keywords: break, if, continue, new, this… The toFixed() function that specifies the number of digits to be displayed after the decimal point. The toPrecision() function specifies the number of digits in a number to be displayed to the user. The toString() function transforms a value into string. Building Dynamic Websites/Session 1/ of 16