10 Useful code snippets for web developers

on Friday, October 30, 2009
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In this post I want to suggest you 10 useful code snippets for web developers based on some frequetly asked questions I received in the past months for my readers. This collection include several CSS, PHP, HTML, Ajax and jQuery snippets.

1. CSS Print Framework

Cascading Style Sheets Framework for web printing. To use this framework download the CSS file here and use this line of code into your web pages


<link rel="stylesheet" href="print.css" type="text/css" media="print">
2. CSS @font-face

This snippet allows authors to specify online custom fonts to display text on their webpages without using images:



@font-face {
font-family: MyFontFamily;
src: url('http://');
}
3. HTML 5 CSS Reset

Richard Clark made a few adjustments to the original CSS reset released from Eric Meyers.

4. Unit PNG Fix

This snippet fixes the png 24 bit transparency with Internet Explorer

5. Tab Bar with rounded corners
This code illustrates how to implement a simple tab bar with rounded corners:


6. PHP: Use isset() instead of strlen()

This snippet uses isset() instead strlen() to verify a PHP variable (in this example $username) is set and is at least six characters long.


<?php 

if (isset($username[5])) {

// Do something... 

}
?>
7. PHP: Convert strings into clickable url

This snippet is very useful to convert a string in a clickable link. I used this snippet for several tutorials;


<? php

function convertToURL($text) {

$text = preg_replace("/([a-zA-Z]+:\/\/[a-z0-9\_\.\-]+"."[a-z]{2,6}[a-zA-Z0-9\/\*\-\_\?\&\%\=\,\+\.]+)/"," <a href=\"$1\" target=\"_blank\">$1</a>", $text);

$text = preg_replace("/[^a-z]+[^:\/\/](www\."."[^\.]+[\w][\.\/][a-zA-Z0-9\/\*\-\_\?\&\%\=\,\+\.]+)/"," <a href="\\" target="\">$1</a>", $text);

$text = preg_replace("/([\s\,\>])([a-zA-Z][a-zA-Z0-9\_\.\-]*[a-z" . "A-Z]*\@[a-zA-Z][a-zA-Z0-9\_\.\-]*[a-zA-Z]{2,6})" . "([A-Za-z0-9\!\?\@\#\$\%\^\&\*\(\)\_\-\=\+]*)" . "([\s\.\,\<])/i", "$1<a href=\"mailto:$2$3\">$2</a>$4",

$text);

return $text;

}

?>
8. jQuery: Ajax call

This is the most simple way to implement an Ajax call using jQuery. Change formId and inputFieldId with the ID of the form and input field you have to submit:

9. CSS Layouts Collections

This page contains a collection of over 300 grids and CSS layout ready to use in your projects. Take a look, it's very useful.

10. Simple versatile multilevel navigation Menu

Several months ago I found this simple code (HTML + CSS + JavaScript for jQuery) to implement a versatile multilevel navigation menu (please send me the original source if you find it!). I think it's the simpler and faster way to do that. The result is something like this:


The only thing you have to do is to create nested lists into a main list with id="nav", in this way: 


<ul id="nav">
<li><a href="#">Link 1</a></li>
<li><a href="#">Link 2</a></li>
<li><a href="#">Link 3</a>
<ul>
<li><a href="#">Link 3.1</a></li>
<li><a href="#">Link 3.2</a></li>
<ul>

</li>


</ul>

...and use this basic CSS code (you have to modify it to customize the layout of this menu with the style of your site!


#nav, #nav ul{margin:0;
padding:0;
list-style-type:none;
list-style-position:outside;
position:relative;
line-height:26px;
}
#nav a:link, 
#nav a:active, 
#nav a:visited{
display:block;
color:#FFF;
text-decoration:none;
background:#444;
height:26px;
line-height:26px;
padding:0 6px;
margin-right:1px;
}
#nav a:hover{
background:#0066FF;
color:#FFF;
}
#nav li{
float:left;

position:relative;
}
#nav ul {
position:absolute;
width:12em;
top:26px;
display:none;
}
#nav li ul a{
width:12em;
float:left;
}
#nav ul ul{
width:12em;
top:auto;
} 
#nav li ul ul {margin:0 0 0 13em;}
#nav li:hover ul ul, 
#nav li:hover ul ul ul, 
#nav li:hover ul ul ul ul{display:none;}
#nav li:hover ul,
#nav li li:hover ul, 
#nav li li li:hover ul, 
#nav li li li li:hover ul{display:block;}


...and this is the JavaScript code for jQuery you have to copy in the tag <head> of the pages that use this menu:


<script type="text/javascript" src="jquery-1.3.2.min.js"></script>
<script type="text/javascript">
function showmenu(){ 
$("#nav li").hover(function(){
$(this).find('ul:first').css({visibility:"visible", display:"none"}).show();

}, function(){
$(this).find('ul:first').css({visibility:"hidden"});
});
}





$(document).ready(function(){ 
showmenu();
});
</script>

If you have better solution, just tell me !

Password generator using JavaScript / jQuery

on Thursday, October 22, 2009
Labels: , / Comments: (0)

The aim is to increase cyber and internet security awareness among surfers. Google and others are joining the move. So I thought I would write a post regarding internet security to add my 2 cents. In this post you will find JavaScript function that generates random passwords of any length as well as jQuery version.



JavaScript Password Generator


$.extend({
  password: function (length, special) {
    var iteration = 0;
    var password = "";
    var randomNumber;
    if(special == undefined){
        var special = false;
    }
    while(iteration < length){
        randomNumber = (Math.floor((Math.random() * 100)) % 94) + 33;
        if(!special){
            if ((randomNumber >=33) && (randomNumber <=47)) { continue; }
            if ((randomNumber >=58) && (randomNumber <=64)) { continue; }
            if ((randomNumber >=91) && (randomNumber <=96)) { continue; }
            if ((randomNumber >=123) && (randomNumber <=126)) { continue; }
        }
        iteration++;
        password += String.fromCharCode(randomNumber);
    }
    return password;
  }
});

This function takes two parameters: integer value for password length and optional boolean value true if you want to include special characters in your generated passwords.

Examples of generated passwords


password(8);

// Outputs: Yrc7TxX3

password(12, true);
//Outputs: C}4_ege!P&#M


jQuery password generator


$.extend({
  password: function (length, special) {
    var iteration = 0;
    var password = "";
    var randomNumber;
    if(special == undefined){
        var special = false;
    }
    while(iteration < length){
        randomNumber = (Math.floor((Math.random() * 100)) % 94) + 33;
        if(!special){
            if ((randomNumber >=33) && (randomNumber <=47)) { continue; }
            if ((randomNumber >=58) && (randomNumber <=64)) { continue; }
            if ((randomNumber >=91) && (randomNumber <=96)) { continue; }
            if ((randomNumber >=123) && (randomNumber <=126)) { continue; }
        }
        iteration++;
        password += String.fromCharCode(randomNumber);
    }
    return password;
  }
});

// How to use
$.password(8);
$.password(12, true);

If you have better solution, just tell me !

Using XMLHttpRequest and a Callback AJAX Example

on Friday, October 16, 2009
Labels: / Comments: (0)

You alread have a webserver installed. If you want to use the SAX Servlet as the backend for this tutorial then you need to have it compiled and deployed.

A big part of WEB 2 is of course AJAX which is asynchronous javascript and xml. We will breakdown an AJAX request down. A complete list of the code is available at the end of this page.

When you load the page the first thing that happens is the creation of an XMLHttpRequest object to handle the xml functions. 


1.  <html>
2.  <head>
3.  <script langua="javascript">
4.  function new_XHR() {
5.      var xhr;
6.      try{
7.          xhr = new ActiveXObject("Msxml2.XMLHTTP");
8.      }catch(e){
9.      try{
10.          xhr = new ActiveXObject("Microsoft.XMLHTTP");
11.          }catch(E){
12.              xhr = false;
13.          }
14.      }
15.      if(!xhr && typeof XMLHttpRequest != 'undefined'){
16.          xhr = new XMLHttpRequest();
17.      }
18.      return xhr;
19.  }

What we are trying to do here, is instantiate an XMLHttpRequest object. As you can see I have not bothered to handle the error if the browser cannot instantiate an object.Now lets have a look at the actual HTML.



49.  <body>
50.  <form>
51.  Name <input id="NameBox" type="text"/>
52.  <a href="javascript:DoCallback()">Send the data without submitting the form</a>
53.  </form>
54.  <div id="MessagePane"/>
55.  </body>
56.  </html>
57.

This shows a textbox and a URL. When you click on the URL it calls the javascript DoCallback function.

The XMLHTTP request



20.
21.  var myxhr;
22.  function DoCallback(){
23.        myxhr = new_XHR();
24.        myxhr.onreadystatechange=MyCallback;
25.        myxhr.open('GET',"saxxmldemo_static.xml?"
26.          +"name="+document.getElementById("NameBox").value);
27.        myxhr.send(null);
28.      }
29.

This sets the callback function onreadystatechange=MyCallback. As you can see this is adding the value in the textbox to the URL. This really doesn't matter if you are using the saxxmldemo_static.xml as this is a static xml file. If you want to use the SAX Servlet example replace line 25 with
myxhr.open('GET', 'http://127.0.0.1:8080/SAXJHelloWorldServlet/saxxmldemo.xml?
This will point to the SAX Servlet which will echo the 'name'. Make sure you have the SAX Servlet example deployed and ready to go.

The Callback



29.
30.  function MyCallback(){
31.      var name;
32.      var message;
33.      if(myxhr.readyState==4 && myxhr.status==200){
34.          var subrootNode = myxhr.responseXML.getElementsByTagName('user-data');
35.          for(i = 0 ; i < subrootNode[0].childNodes.length ; i++){
36.              var node = subrootNode[0].childNodes[i];
37.              if(node.tagName=="name")
38.                  name=node.firstChild.nodeValue;
39.              else if(node.tagName=="message")
40.                  message=node.firstChild.nodeValue;
41.              else{}
42.          }
43.          document.getElementById("MessagePane").innerHTML = "Hey "+name+" the server says \""+message+"\"";
44.      }
45.  }

This is the function that gets called when the XMLHttpRequest object changes state i.e receives a response. As you can see on line 33, we are only interested in readyState=4 (document has loaded) and status 200 which means successful. You should have more error handling code here. You can use childNodes to drill down and extract the information or you can use getElementsByTagName(). The message is written to the html div with the id 'MessagePane' using innerHTML.


childNodes[n]
__childNodes[0] (.firstChild)
__childNodes[1]
____childNodes[0] (.firstChild)
____childNodes[1]
__childNodes[2]

The xmldemo_static.xml

 1. <?xml version="1.0" encoding="UTF-8"?>
 2. <user-data>
 3.     <name type="Alias">Doctor Octopus</name>
 4.     <message type="greeting">Hello there from the SAX servlet</message>
 5. </user-data>

Entire listing of index.html


 1. <html>
 2. <head>
 3. <script langua="javascript">
 4. function new_XHR() {
 5.     var xhr;
 6.     try{
 7.         xhr = new ActiveXObject("Msxml2.XMLHTTP");
 8.     }catch(e){
 9.     try{
10.         xhr = new ActiveXObject("Microsoft.XMLHTTP");
11.         }catch(E){
12.             xhr = false;
13.         }
14.     }
15.     if(!xhr && typeof XMLHttpRequest != 'undefined'){
16.         xhr = new XMLHttpRequest();
17.     }
18.     return xhr;
19. }
20. 
21. var myxhr;
22. function DoCallback(){
23.       myxhr = new_XHR();
24.       myxhr.onreadystatechange=MyCallback;
25.       myxhr.open('GET',"http://127.0.0.1:8080/SAXJHelloWorldServlet/saxxmldemo.xml?"
26.         +"name="+document.getElementById("NameBox").value);
27.       myxhr.send(null);
28.     }
29. 
30. function MyCallback(){
31.     var name;
32.     var message;
33.     if(myxhr.readyState==4 && myxhr.status==200){
34.         var subrootNode = myxhr.responseXML.getElementsByTagName('user-data');
35.         for(i = 0 ; i < subrootNode[0].childNodes.length ; i++){
36.             var node = subrootNode[0].childNodes[i];
37.             if(node.tagName=="name")
38.                 name=node.firstChild.nodeValue;
39.             else if(node.tagName=="message")
40.                 message=node.firstChild.nodeValue;
41.             else{}
42.         }
43.         document.getElementById("MessagePane").innerHTML =
44.                                     "Hey "+name+" the server says \""+message+"\"";
45.     }
46. }
47. 
48. </script>
49. </head>
50. <body>
51. <form>
52. Name <input id="NameBox" type="text"/>
53. <a href="javascript:DoCallback()">Send the data without submitting the form</a>
54. </form>
55. <div id="MessagePane"/>
56. </body>
57. </html>
Hide line numbers

If you have better solution, just tell me !