Web Designing

Some PHP Tips

2011-09-01T05:55:00.001-07:00

- If a method can be static‚ declare it static. Speed improvement is by a factor of 4.

- echo is faster than print.

- Use echo’s multiple parameters instead of string concatenation.

- Set the maxvalue for your for-loops before and not in the loop.

- Unset your variables to free memory‚ especially large arrays.

- Avoid magic like __get‚ __set‚ __autoload

- require_once() is expensive

- Use full paths in includes and requires‚ less time spent on resolving the OS paths.

- If you need to find out the time when the script started executing‚ $_SERVER[’REQUEST_TIME’] is preferred to time()

- See if you can use strncasecmp‚ strpbrk and stripos instead of regex

- str_replace is faster than preg_replace‚ but strtr is faster than str_replace by a factor of 4

- If the function‚ such as string replacement function‚ accepts both arrays and single characters as arguments‚ and if your argument list is not too long‚ consider writing a few redundant replacement statements‚ passing one character at a time‚ instead of one line of code that accepts arrays as search and replace arguments.

- It’s better to use select statements than multi if‚ else if‚ statements.

- Error suppression with @ is very slow.

- Turn on apache’s mod_deflate

- Close your database connections when you’re done with them

- $row[’id’] is 7 times faster than $row[id]

- Error messages are expensive

- Do not use functions inside of for loop‚ such as for ($x=0; $x < count($array); $x) The count() function gets called each time.

- Incrementing a local variable in a method is the fastest. Nearly the same as calling a local variable in a function.

- Incrementing a global variable is 2 times slow than a local var.

- Incrementing an object property (eg. $this->prop++) is 3 times slower than a local variable.

- Incrementing an undefined local variable is 9-10 times slower than a pre-initialized one.

- Just declaring a global variable without using it in a function also slows things down (by about the same amount as incrementing a local var). PHP probably does a check to see if the global exists.

- Method invocation appears to be independent of the number of methods defined in the class because I added 10 more methods to the test class (before and after the test method) with no change in performance.

- Methods in derived classes run faster than ones defined in the base class.

- A function call with one parameter and an empty function body takes about the same time as doing 7-8 $localvar++ operations. A similar method call is of course about 15 $localvar++ operations.

- Surrounding your string by ’ instead of " will make things interpret a little faster since php looks for variables inside "..." but not inside ’...’. Of course you can only do this when you don’t need to have variables in the string.

- When echoing strings it’s faster to separate them by comma instead of dot. Note: This only works with echo‚ which is a function that can take several strings as arguments.

- A PHP script will be served at least 2-10 times slower than a static HTML page by Apache. Try to use more static HTML pages and fewer scripts.

- Your PHP scripts are recompiled every time unless the scripts are cached. Install a PHP caching product to typically increase performance by 25-100% by removing compile times.

- Cache as much as possible. Use memcached - memcached is a high-performance memory object caching system intended to speed up dynamic web applications by alleviating database load. OP code caches are useful so that your script does not have to be compiled on every request

- When working with strings and you need to check that the string is either of a certain length you’d understandably would want to use the strlen() function. This function is pretty quick since it’s operation does not perform any calculation but merely return the already known length of a string available in the zval structure (internal C struct used to store variables in PHP). However because strlen() is a function it is still somewhat slow because the function call requires several operations such as lowercase & hashtable lookup followed by the execution of said function. In some instance you can improve the speed of your code by using an isset() trick.

Ex.
if (strlen($foo) < 5) { echo "Foo is too short"; }
vs.
if (!isset($foo{5})) { echo "Foo is too short"; }

Calling isset() happens to be faster then strlen() because unlike strlen()‚ isset() is a language construct and not a function meaning that it’s execution does not require function lookups and lowercase. This means you have virtually no overhead on top of the actual code that determines the string’s length.

- When incrementing or decrementing the value of the variable $i++ happens to be a tad slower then ++$i. This is something PHP specific and does not apply to other languages‚ so don’t go modifying your C or Java code thinking it’ll suddenly become faster‚ it won’t. ++$i happens to be faster in PHP because instead of 4 opcodes used for $i++ you only need 3. Post incrementation actually causes in the creation of a temporary var that is then incremented. While pre-incrementation increases the original value directly. This is one of the optimization that opcode optimized like Zend’s PHP optimizer. It is a still a good idea to keep in mind since not all opcode optimizers perform this optimization and there are plenty of ISPs and servers running without an opcode optimizer.

- Not everything has to be OOP‚ often it is too much overhead‚ each method and object call consumes a lot of memory.

- Do not implement every data structure as a class‚ arrays are useful‚ too

- Don’t split methods too much‚ think‚ which code you will really re-use
You can always split the code of a method later‚ when needed

- Make use of the countless predefined functions

- If you have very time consuming functions in your code‚ consider writing them as C extensions.

- Profile your code. A profiler shows you‚ which parts of your code consumes how many time. The Xdebug debugger already contains a profiler. Profiling shows you the bottlenecks in overview

- mod_gzip which is available as an Apache module compresses your data on the fly and can reduce the data to transfer up to 80%

Example 3. Function with Arguments

2011-09-01T05:21:00.001-07:00

<html>

<head>

<script language="JavaScript">

function myfunction(txt)

{

alert(txt)

}

</script>

</head>

<body>

<form>

<input type="button" onclick="myfunction('Hello')" value="Call function">

</form>

<p>By pressing the button, a function with an argument will be called. The
function will alert this argument.</p>

</body>

</html>

Example 2. Creating Functions in JavaScript

2011-09-01T05:18:00.000-07:00

<html>

<head>

<script language="JavaScript">

function myfunction()

{

alert("HELLO")

}

</script>

</head>

<body>

<form>

<input type="button" onclick="myfunction()" value="Call function">

</form>

<p>By pressing the button, a function will be called. The function will alert a
message.</p>

</body>

</html>

Example 1. Using Variables in JavaScript

2011-09-01T05:15:00.001-07:00

Example 1. Using Variables in JavaScript

<html>

<body>

<script language="JavaScript">

var name = "Hege"

document.write(name)

document.write("<h1>"+name+"</h1>")

</script>

<p>This example declares a variable, assigns a value to it, and then displays
the variable.</p>

<p>Then the variable is displayed one more time, only this time as a
heading.</p>

</body>

</html>

JavaScript Objects

2011-09-01T05:13:00.000-07:00

Java Script Objects

Java Script is object based language, it is not support completley OOPs (Object Oriented Programming) features, you may confuse how you create object from another object rather than create object from class normally we do it in any object oriented programming language like C++, Java or dot net.

Javascript support both built in objects as well as you can create your own custom objects, there are more than 20 objects, in these section we know in details about them.

JavaScript's built in objects from the core of the logical event-driven environ meant within which scripts are designed. These objects (frames, windows, documents, forms, and son on) behave in predictable ways and can be manipulated through their well-defined properties and methods. Built in objects are those that are automatically included in the java script environment; you don not have to create them or do anything to make them accessible other refer to them within a script whenever they are nodded.

Sr.	Objects	Object Description
1	Anchor	Consist of text string identifying a hypertext link in an HTML document.
2	Button	Lets you define and control a push button that appears on an HTML from.
3	Checkbox	Lets you exert control over a check box within an HTML form.
4	Date	Provides access to date and time functions within a Java Script.
5	Document	Consist of properties and methods associated with a specific HTML document file.
6	Element Array	Represents a list of individual from elements accessible through an indexed array.
7	Form	Consists of the properties and methods associated with individual forms in an HTML document and form objects.
8	Frame	Consists of an individual scrollable windows established through tag and capable of displaying HTML documents.
9	Hidden	Provides access to hidden objects that exits on a form.
10	History	Consists of an accessible list of a URL links compiled during the course of a user navigating through a series of web pages.
11	Link	Represents a hypertext link in the form of text or image
12	Location	Provides specific data on the currently active URL.
13	Math	Performs a wide range of mathematical functions.
14	Navigator	Provides version of Navigator
15	Password	Provides access to that portion of an HTML form that is used to process text field containing a password. entered characters are marked as asterisks.
16	Radio	Lets you control access to a radio button embedded in an HTML form.
17	Reset	Provides access to a reset button appearing on an HTML Form.
18	Select	Provides indexed array access to the contents of a selection list or a scrolling list appearing within an HTML form.
19	String	Perform string manipulation.
20	Submit	Perform processing of submit buttons that have been defined in an HTML document.
21	Text	Provides access to text input fields that are used on a HTML form.
22	Textarea	Offers processing of scrollable, multiline text blocks that can be embedded within an HTML form.
23	Window	Represents the second highest level objects in the hierarchy.

What is Java Script

2011-09-01T05:12:00.001-07:00

What is Java Script? JavaScript is an object-based scripting language designed primarily for HTML (Hypertext Markup Language), It supports both IE (internet Explorer) and Netscape Navigator and all other major web browser. Java script can be used for both client side as well as server side in web development. It is not a programming language it can not create executable code while compiling, it is embed in document and while pursing the html document it executes the script, it is an object-based scripting language, while reasonably simple in syntax, construction, and features, the object-based nature of JavaScript still offers programmers significant power and flexibility through the ability to create functions and new objects.

An object in the context of JavaScript, is a collection of properties and methods consisting a set of defined characteristics that you can view and modify, and which you can interact. Methods are the techniques that are used to perform action involving objects and properties. For example statement like Document. Write("Welcome to Javascript") here Document is the object, Write is the method of Document object, JavaScript follows event driven sequence. the events determine the program flow and event handlers determine what happen when these event occurs.

Where to Write Java Script
You can write javascript in body or head section depend on your requirement or you can write java script in a sepeate file with extension ".js" and includes it in your HTML document with

Basic of JavaScript

2010-07-03T07:37:00.001-07:00

Java Script Syntax and Features

1. There is no need to declare variable, however
you can

define variable with var keyword.

2. Curl braces ({}) are separated two code
blocks.

3. White space and carriage return are not count
in code statement.

4. Semicolon (;) terminate a statement.

5. For single line comment use double slash
(//).

6. For multi line comment use /* and */ sign.

Variable name rules

Variable are place holder of value used in run time by the program, every
variable has an unique name within the scope of execution, while declaring the
variable always keep un mind.

1. Must start with number and underscore (_)

2. Use any alphanumeric character.

3. Do not use any special character and white space.

4. Variable name are case sensitive.

5. Do not use keyword as variable name.

Operator and order of precedence

[]

()

>>>

<<=

>>=

>>>=

String
Operators

Concatenation

Comparison Operators

	==	Equal To
	!=	Not Equal To
	<	Less Than
	>	Greater Than
	>=	Greater than or equal to
	<=	Less than or equal to

Arithmetic Operators

	*	Multiplication
	/	Division
	+	Addition
	-	Subtraction

Logical
Operators

AND

Assignment
Operator

Assignment

Keyword List

In
JavaScript there are 50 keywords, this are reserve word in the language you can
not use this keyword in naming of variable or function.

abstract	float	public
boolean	for	return
break	function	short
byte	goto	static
case	if	super
catch	implements	switch
char	import	synchronized
class	in	this
const	instanceof	throw
continue	int	throws
default	interface	transient
do	long	true
double	native	try
else	new	var
extends	null	void
false	package	while
final	private	with
finally	protected

Conditional
Construct

1. if.. else ..

2. switch case

Looping Construct

1. for

2. while

User Define Function

function <functionname>(argument)

{

//function body

return <value>

}

Some Sample Small Programmes

2010-07-03T07:35:00.001-07:00

1. Writing text on the browser window
<html>
<body>
<script language="JavaScript">
document.write("Hello World!")
</script>
</body>
</html>

2. Writing Formatted Text on the Browser
<html>
<body>
<script language="Java Script">
document.write("<h1>Hello World!</h1>")
</script>
</body>
</html>

3. Using HEAD Section
<html>
<head>
<script language="JavaScript">
function message(){
alert("This alert box was called with the onload
event")
}
</script>
</head>
<body onload="message()">
</body>
</html>

4. Using BODY Section
<html>
<head>
</head>
<body>
<script language="JavaScript">
document.write("This message is written when the
page loads")
</script>
</body>
</html>

<html>
<head>
</head>
<body>
<script src="myscript.js">
</script>
<p>The actual script is in an external script
file called "myscript.js".</p>
</body>
</html>

Try yourself.
1. Load any text editor (Notepad, WordPad, Word,
TextPlus)
2. Create the HTML file and save it, with .HTM or
.HTML extension. and write following HTML and javascrpt.
   <html>
   <body>
   <script language="JavaScript">
   document.write("Hello to JavaScript World!")
   </script>
   </body>
   </html>
3. Open saved file in Browser (IE, Netscape) to
view it will display Hello to JavaScript World!.

Java Scripting

2010-07-03T07:33:00.000-07:00

What is Java Script?
JavaScript is an object-based scripting language designed primarily for HTML (Hypertext Markup Language), It supports both IE (internet Explorer) and Netscape Navigator and all other major web browser. Java script can be used for both client side as well as server side in web development. It is not a programming language it can not create executable code while compiling, it is embed in document and while pursing the html document it executes the script, it is an object-based scripting language, while reasonably simple in syntax, construction, and features, the object-based nature of JavaScript still offers programmers significant power and flexibility through the ability to create functions and new objects.
An object in the context of JavaScript, is a collection of properties and methods consisting a set of defined characteristics that you can view and modify, and which you can interact. Methods are the techniques that are used to perform action involving objects and properties. For example statement like Document. Write("Welcome to Javascript") here Document is the object, Write is the method of Document object, JavaScript follows event driven sequence. the events determine the program flow and event handlers determine what happen when these event occurs.

Where to Write Java Scrip
You can write javascript in body or head section depend on your requirement or you can write java script in a sepeate file with extension ".js" and includes it in your HTML document with