Improve Ajax Performance

Following are few steps to Improve Ajax Performance

1. First try to Reduce the Number of Ajax Call
2. If same call send again, abort the previous call
3. If ajax call is executing, and user go for another link, then cancel the previous one.
4. Use GET Method, As its Fast but less secure
5. Reduce the Amount of data transmitted
   a. Only Required parameter in Ajax Request
   b. Only Required Response in Ajax Request
6. Optimize your Server  

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PHP Captcha Code Example Code Snippets

A CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a type of challenging-response test used in computer field to determine whether user is Human OR robot program. Captcha is used in website to confirm that your website is accessing by a human being not machine. We can add captcha in multiple form/pages of website.

It reduce the risk of hacking/damage of website. It also help to secure the web server.


Follow Simple Steps to add captcha in your website.

1. Copy the following code and put in createCaptch.php

session_start();
//Let's generate a totally random string using md5
$md5_hash_no = md5(rand(0, 999));
//We don't need a 32 character long string so we trim it down to 5
$security_code = substr($md5_hash_no, 15, 5);
$_SESSION['captcha'] = $security_code;

//Set the image width and height
$width = 148;
$height = 37;

//Create the image resource
$image = ImageCreate($width, $height);

//We are making three colors, white, black and gray
$white = ImageColorAllocate($image, 255, 255, 255);
$black = ImageColorAllocate($image, 0, 0, 0);
$grey = ImageColorAllocate($image, 204, 204, 204);

//Make the background black
ImageFill($image, 0, 0, $grey);

//Add randomly generated string in white to the image
ImageString($image, 8, 50, 10, $security_code, $black);

//$font = 'font1.ttf';
//imagettftext($image, 18, 0, 15, 28, $black, $font, $security_code);
//Throw in some lines to make it a little bit harder for any bots to break
ImageRectangle($image, 0, 0, $width - 1, $height - 1, $grey);

// prevent client side  caching
header("Expires: Wed, 1 Jan 1997 00:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");


//Tell the browser what kind of file is come in
header("Content-Type: image/jpeg");

//Output the newly created image in jpeg format
ImageJpeg($image);

2. In the Form add following

<input name="ccode" type="text" /> <img src="createCaptch.php" title="Captcha Code" />

3. Validate the captcha

session_start();
if($_POST['ccode']==$_SESSION['captcha']){
    //valid 
}ELSE{
    //Invalid
}

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