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Java Script
- 1. Java Script Java Script is one of the 3 languages all web developers must learn: ๏ HTML โ To define the content of webpages ๏ CSS โ To specify the layout (Style) of web pages ๏ JS โ To program the behavior of the webpage. Introduction to JS ๏ JavaScript is a lightweight, interpreted scripting language with object- based capabilities that allows you to build interactive HTML pages. ๏ JS designed to add interactivity with HTML pages. ๏ JS is Multi P ๏ aradine. ๏ A JS is usually embedded directly into HTML pages. ๏ JS is an interpreted language (means that scripts execute without preliminary compilation). ๏ Browser must have built-in (JavaScript) interpreter. ๏ Interpreted, not compiled. ๏ More relaxed syntax and rules ๏ท Fewer and โlooserโ datatypes ๏ท Variables donโt need to be declared ๏ Key construct is the function rather than the class ๏ Contained within a webpage and integrates with its HTML/CSS content. ๏ It can be used for validation for login. ๏ท Are Java and Java Script the same? ๏ They are completely two different languages ๏ท The Two scripting languages are: ๏ Client site scripting languages ๏ Server site scripting languages TO create interactive UI in a webpage Swapping, rollovers, slideshows, clickable images, Date time stuff (e.g.: clocks, calenders)
- 2. The HTML DOM (Document Object Model) ๏ท When a webpage is loaded, the browser creates a Document Object Model of the page. ๏ท The HTML DOM model is constructed as a tree of objects. Document Root element<html> Left Right Element <head> Element <body> Element <title> Attribute โhrefโ Element <a> Element <h1> Text โMy titleโ Text: โMy linkโ Text: โMy headerโ What is the DOM? The DOM is a W3C (World Wide Web Consortium) standard. The DOM defines a standard for accessing documents: โThe 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 documentโ DOM With object model, java script gets all the power it needs to create dynamic HTML: Javascript can Change the HTML Content:
- 3. One of the many JS HTML methods is getElementsById(). Find an HTML element (with id=โdemoโ) and changes the element content (innerHTML) to โHello JavaScriptโ: Example: Document.getElementById(โdemoโ).innerHTML=โHello JavaSCriptโ; DAY 3 DOM (Document Object Model): When the object model, JS gets all the power it needs to create dynamic HTML. ๏ JS can change all the HTML elements in the page. ๏ JS can change all the HTML attributes in the page. ๏ JS can change all the CSS-styles in the page. ๏ JS can change remove existing HTML elements and attributes. ๏ JS can add new HTML elements and attributes. ๏ JS can react to all existing HTML events in the page ๏ JS can create a new HTML events in the page. The HTML DOM is a standard object model and programming interface for HTML. It defines: The HTML elements as objects. ๏ท The properties of all HTML elements ๏ท The methods to access all HTML elements ๏ท The events for all HTML elements. Class Definition: ๏ท Class is a representation of objects. Or class is a mechanism to create objects. ๏ท The class is like a cookie