JavaScript DOM Nodes and Exception Handling Tutorial for beginners

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JavaScript DOM Nodes and Exception Handling
Tutorial Videos for Beginner by
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Highlights

• Document Object Model Nodes
• 1. DOM Nodes
• 2. DOM Levels
• 3. DOM Interfaces
• Debugging and Exception Handling
• 1. Try-catch-Finally statement
• 2. Error event and Browser Sniffing
• 3. JSLint Checker

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DOM Nodes

• HTML elements are called as nodes
• Create the node in order to insert a new element
  into the DOM.
• Syntax var paragraph document.createElement(
  q")
• To add text to the ltqgt element, you must create a
  text node first.
• Syntax var node document.createTextNode("This
  is a new para")
• Appending the text node to the ltqgt element is as
  follows
• Syntax paragraph.appendChild(node)

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DOM Levels

• It has three levels. DOM Level 1, DOM Level 2,
  DOM Level 3.
• DOM Level 1 divided into two parts i.e. Core part
  and HTML, defines the core elements of the DOM.
• DOM level 2 consist six dissimilar
  specifications, they are DOM2 Core, Views,
  Events, Style, Traversal and Range, and the DOM2
  HTML.
• DOM2 extends Dom1 elements and adds events.
• DOM3 has five dissimilar specifications, they are
  DOM3 Core, Load and Save, Validation, Events, and
  XPath.
• DOM 3 extends DOM2 and adds new elements and
  events.

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DOM Interfaces

• Interfaces are use to manage HTML, XML and SVG
  documents.
• Provides a structured representation of the
  document.
• Specifies approach to access and manipulate apps
  inner representation of a document.
• DOM application documents representation depends
  on Interfaces. 
• Obsolete DOM interfaces, HTML interfaces, HTML
  element interfaces, Obsolete HTML interfaces, SVG
  interfaces, SVG element interfaces, SVG data type
  interfaces, SMIL related interfaces are different
  types of DOM interfaces.

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Debugging and Exception handling

• Web Console, Browser console are the chrome
  browser web developer options useful for
  debugging.
• Firefox provides Error console and Browser
  debugger for debugging
• Error console is outdated and is no longer
  enabled in Firefox by default. Use the Web
  Console or the Browser Console instead.
• JavaScript will show three types of errors in
  programming Syntax Errors, Runtime Errors, and
  Logical Errors.

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Debugging and Exception handling

• Syntax errors are also called as parsing errors
  which occur at compile time
• If syntax error occurs the code thread only would
  be affected remaining threads gets executed
•  Runtime errors are also called as exceptions
  which occur during execution.
• Exceptions also affect the thread in which they
  occur, other JavaScript threads continues their
  execution.
• Logic errors can be the most difficult type of
  errors to track down. 
• Logic errors are the outcome of a syntax or
  runtime error. 

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Try , Catch, Finally Statement

• Every try block will have exactly one catch block
  or one finally block.
• When an exception occurs in the try block, it
  throws the error 
• Syntax try  //code that may throw exception
    
• catch(Exception class Name ref) or finally
• catch block handles the errors thrown by try
  block
• In the final the optional finally block executes
  unconditionally after try/catch.

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Error Event and Browser Sniffing

• Error event interface represents events providing
  information correlated to exceptions in scripts
  or in files.
• ErrorEvent() constructor creates
  an ErrorEvent event with the user specified
  parameters.
• Browser sniffing is the technique used to
  determine the  visitor web browser, to  serve
  browser appropriate content to the visitor.
• Browser sniffing also called as browser detect.

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JSLint Checker

• JSLint Checker is JavaScript code quality checker
  tool.
• Helps to notice exceptions and possible troubles
  in code.
• Supports very quick and easy way to check code.
• Analyzes JavaScript source code to advise about
  quality troubles. 
• Provides Limited number of configuration options.
• Difficult to identify which ruling is causing
  errors.

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Exception Handling Tutorial Videos for
Beginner by
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