All about open systems

Difference between Well Formed XML and Valid XML? What is Broken Xml?

1) Well Formed XML documents are the one that meets all the well-formedness constraints given in this specification.

XML document are well formed if they are syntactically correct

i.e. An XML document with correct syntax is called "Well Formed".

2) Valid XML A Well Formed XML is a valid XML, when the well-formed XML document follows the rules (document structure and rule) specified by the XML Schema or DTD.

An XML document validated against a DTD, Schema is "Well Formed" and "Valid".

Valid XML document is implicitly well-formed, but well-formed may not be valid

3) Broken XML documents are simply those which fail to follow the rules required for a document to be either well-formed or valid.

Basic rules of syntax

1) Every open tag must be closed.

2) The open tag must exactly match the closing tag: XML is case-sensitive.

3) All elements must be embedded within a single root element.

4) Child tags must be closed before parent tags.

5) A well-formed document has correct XML tag syntax, but the elements might be invalid for the specified document type.

Different Casing styles or Naming conventions in programming. What is Camel casing Pascal casing Upper casing Lower casing and Difference between them

There are mainly four different casing styles that is followed while programming, they are

1) Camel casing (also called as lower camel casing)

2) Pascal casing (also called as upper camel casing)

3) Upper casing

4) Lower casing

Camel casing – Capitalizes the first character of each word except the first word

In camel casing the first letter of the first word is in lower casing.

If any words are concatenated then the first letter of the concatenated word is in uppercase followed by lower case characters.

Example: calculateInterest, operationResults, propertyDescriptor, htmlTag

Usage:

i) Variable names

ii) Object reference variables

iii) method arguments

Pascal casing – Capitalizes the first character of each word (including acronyms over two letters in length)

In Pascal casing the first letter of the word is in uppercase following characters are in lowercase.

If any words are concatenated then the first letter of the word is also in uppercase followed by lower case characters.

Example: DataAccessClass, PropertyDescriptor, HtmlTag, IOStream

Usage:Class names

Difference between display:none and visibility:hidden in CSS. Hide content in HTML through CSS using visibility and display properties

Introduction: In a Web Page we can hide an HTML element from being displayed using two ways that is by setting the display property to none or by setting the visibility property to hidden in CSS.

In this post we will explore the difference between the two

When we hide an element using visibility property,it will cause the space to be unused that is the space will be preserved as it is i.e. there will be a blank/empty space.

Whereas when hiding an element using the display property will cause the space to be used by other elements.

Example:

Code explaining the difference

<head>

<title>Hiding Elements</title>

</head>

<html>

<body>

function hideSampleText1() {

document.getElementById('Text1').style.visibility = 'hidden';

}

function showSampleText1() {

document.getElementById('Text1').style.visibility = 'visible';

}

function hideSampleText2() {

document.getElementById('Text2').style.display = 'none';

}

function showSampleText2() {

document.getElementById('Text2').style.display = 'block';

}

</script>

<h1 id="Text1">Hide using Visibility</h1><hr>

<h1 id="Text2">Hide using Display</h1><hr>

Using Visibility:<br/>

Using Display:<br/>

</body>

</html>

What are callback functions in javascript and its uses. How callback functions are used in jQuery

A callback function is a function that is passed to another function as a parameter.

A callback function is also known as a higher-order function.

A callback function is essentially a pattern (an established solution to a common problem), and therefore, the use of a callback function is also known as a callback pattern.

A callback function can be a Named function or an anonymous function.

Example1	Example2
$("#btn_1").click(function() { alert("Button 1 Clicked"); });	setTimeout(function () { alert('hello'); }, 1000);