Javascript: DOM, Window Object, Page Load and URL Encoding/Decoding Examples

This software (wordpress.com) is so good at omitting scripts from your post and it’s true that if you wanna benefit from the glory of it all use the actual product (wordpress.org). I do not have my own domain for that though, so in spite of the absence of an actual demonstration, here are some useful javascript source codes!

window element

This code shows how to display a popup window.

onclick="window.open('test.html', 'windowname1', 'width=200, height=77'); return false;"

Full window properties

function popup(url)
{
 var width  = 500;
 var height = 500;
 var left   = (screen.width  - width)/2;
 var top    = (screen.height - height)/2;
 var params = 'width='+width+', height='+height;
 params += ', top='+top+', left='+left;
 params += ', directories=no';
 params += ', location=no';
 params += ', menubar=no';
 params += ', resizable=no';
 params += ', scrollbars=yes';
 params += ', status=no';
 params += ', toolbar=no';
 newwin=window.open(url,'windowname5', params);
 if (window.focus) {newwin.focus()}
 return false;
}

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The DOM

This code shows how to change the innerHTML value of a tag, change the color of a text, change the options of a select, make some page contents disappear, disable radio buttons, mark radio buttons as checked by default and basically how to user a switch function in JS and use the function getElementByID().

<script language="javascript">
function act(n){
	switch(n){
		default: break;
		case 1:{
			document.getElementById("targetObj").innerHTML =
"<p id='helloworld'>hello world</p>";
			replaceSelectOpt("change color of 'hello world'", 2);
			break;
		}
		case 2:{
			document.getElementById("helloworld").style.color = "red";
			replaceSelectOpt("change me into useless radio buttons", 3);
			break;
		}
		case 3:{
			r = "<input type='radio' name='rad' checked='true'>huhuhuh";
			r = r + "<input type='radio' name='rad' disabled='true'>nahnah";
			document.getElementById("thejester").innerHTML = r;
			s = "<a href='javascript:void(0)' onClick='act(4)'>
I am tired. Make me vanish.</a>";
			document.getElementById("helloworld").innerHTML = s;
			break;
		}
		case 4:{
			document.getElementById('thejester').innerHTML = "";
			document.getElementById('targetObj').innerHTML = "";
		}
	}
}

function replaceSelectOpt(txt, nxt){
	full = "<option>Choose!</option><option onClick=
'act(" + nxt + ")'>" + txt + "</option>";
	document.getElementById("you_have_no_choice_but_to_follow").innerHTML = full;
}

</script>

<div id="thejester">
	<select id="you_have_no_choice_but_to_follow">
	<option>Choose!</option>
	<option onClick="act(1)">show me a paragraph</option>
	</select>
</div>

<br>
<div id="targetObj"></div>

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history.go() function

Go to previous page

For whatever purpose it may serve, you may use the history() function to navigate towards a specific page in your history.

history.go(-1);

Reload Page

history.go(0);

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escape() and unescape() functions //url encode and decode

These are the javascript counterparts for PHP’s rawurldecode and rawurlencode.

<input type="text" size="100" onKeyPress=
"document.getElementById('s').innerHTML=escape(this.value)">
<div id="s"></div>

Jeassshhh… There’s too much code here….(X_+)

Useful PHP Functions

These are three of my favorite PHP functions.

string file_get_contents ( string $filename [, int $flags [, resource $context [, int $offset [, int $maxlen ]]]] ) – Get the contents of a url.

Example:

// following code will display the contents of the web page www.example.com $url = “http://www.example.com”; $contents = file_get_contents($url); echo $contents;

bool mail ( string $to , string $subject , string $message [, string $additional_headers [, string $additional_parameters ]] ) – Requires an email server. This functions programatically sends an email based on the given parameters.
Example:

// send an email to someone@somedomain.com $to=”someone@somedomain.com $subj = “example”; $message=”this is an email”; if(mail($to, $subj, $message)) echo “Email was sent”; else echo “Email sending failed.”;

int fwrite ( resource $handle , string $string [, int $length ] ) - Write something to a file. Note that the file and it’s parent directory should have permissions granted to a user such as “apache” or “www-data”.

Example:

// open a file called test.txt and if it does not exist, attempt to create it; place the pointer at the begining of the file $handle = fopen(“test.txt”, “a+”); $data = “I am programatically written.\n”; fwrite($handle, $data); fclose($handle);

I’ll stick with these 3 functions for the meantime. With this though, you can make programs such as:

• A simple email interface.
• A logging system using just the last function
• A proxy browser or something.

PHP SESSION

This post was originally titled "PHP Developer Essentials" which was what I really wanted to post instead of "PHP Essentials". But as I was at it, I got really bored and I realize, I really just wanted to list all my favorite or let me just say "mostly used" php functions.

But to preserve the efforts, let me just leave what I have already typed here—Creating a session with PHP.

Creating a Session

login.php

<?php $login_name = $_POST['username']; $login_password = $_POST['password']; if($login_name==’admin’ && $login_password==’@dm!n’){    session_start();    session_cache_expire(15);    $_SESSION['user'] = $_POST['username'];    header("Location: ‘home.html’"); } else{    die("Authentication Failed"); } ?>

What this simple program does, is get post data from a form that uses the POST method and defined the URL of this code as the form target. The form will look like:

<form action=’login.php’ method=’post’> Username: <input type=’text’ name=’username’> Password: <input type=’password’ name=’password’> <input type=’submit’ value=’Login’>

After retrieving post data, it will validate the user inputs then start a session and store the login data (username) in a session variable called (user). It will then set the window location to the home page using the header() function.

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PHP Essentials

Learn PHP quick! Here are the php elements and functions which I find essential in developing applications with PHP.

Basic Syntax

<?php echo “hello world”; ?>

The output would be:

hello world

Variables

Variables are represented by a dollar sign ($) and does not require type declaration.

<?php $a = “this is a string”; $b = 1; $c = 2; $d = $b + $c; echo $d . ” is an integer” . “<br>”; echo $a; ?>

The output would be:

3 is an integer this is a string

Basic Conditions

Here are some of the most basic conditions:

<?php $a = 1; $b = 2; if($a==$b){ echo “a is equal to b” . “<br>”; } else if($a!=$b){ echo “a is not equal to b” . “<br>”; } if($a>=$b) or $a==1){ echo “a is greater than or equal to b or a is equal to 1″; } ?>

The output would be:

a is not equal to be a is greater than or equal to b or a is equal to 1

….Anyway, this is supposed to be a reference, not a tutorial. To really learn php, go to this site!