On Sep 25, 12:50*pm, jackson.ra...@gmail.com wrote:
Hello,
Hello.
>
Let me explain my situation first. I have *bought a 3rd party tool
that runs a PHP script and gives me some HTML code which I can
directly use in my pages.
The code generated is normal HTML code, example
[snip]
Ok. Understand what's first, first.
1) HTML = HyperText Markup Language; PHP = PHP Hypertext Processor. So
here we go:
If you have the PHP extension installed unto a web server, it means
that the server, as it reads the requested file from the client, that
file will be caught by the PHP parser and execute any script it finds,
replace the script portion of the file by whatever output it produces,
and the server will send that portion instead of the PHP script. (This
is the same thing with any other server-side scripting language. (I'm
explaining briefly here.)
For example, if your equest the file hello.php, and the file looks
like this:
<html>
<head>
</head>
<body>
<?php echo '<p id="hello">Hello world!</p>'; ?>
</body>
</html>
You will receive:
<html>
<head>
</head>
<body>
<p id="hello">Hello world!</p>
</body>
</html>
Now, PHP doesn't understand the HTML part of you page. In fact, it
doesn't know it at all. All it knows (in this example anyway) is that
there's a string that contains '<p id="hello">Hello world!</p>', and
that it outputs it. Thus, PHP can replace portion of the strings it
knows BEFORE it sends it to the client. But if you want to modify the
HTML only from the client side, THEN you make use of Javascript. So,
let's change the code a little:
<html>
<head>
</head>
<body>
<?php echo '<p id="hello">Hello world!</p>'; ?>
<script type="text/javascript">
var el = document.getElementById("hello");
el.innerHTML += "<br />Bye world!";
</script>
</body>
</html>
You will receive from the server this file:
<html>
<head>
</head>
<body>
<p id="hello">Hello world!</p>
<script type="text/javascript">
var el = document.getElementById("hello");
el.innerHTML += "<br />Bye world!";
</script>
</body>
</html>
NOTE : the <scripttag is still there! That's because it has not yet
been executed! But first, the browser (IE/Firefox/etc.) has to parse
that data too. This is because HTML is markup language, and the
browser converts the markups into the DOM (Data Object Model); the DOM
is organized in a tree-like structure in the memory of the browser.
So, this is why everything is attached to the document object in
javascript. (Because Javascript talks to the DOM, not the HTML.) In
your example, the DOM would look like this:
object:window
...DOMElement:body
.....DOMElement:p{id:"hello"}
.......textElement:Hello world!
NOTE : this is a very simplified representation of the DOM tree, for
explanation purposes.
As you may have noticed, the <scripttag is not there. This is
because, as PHP scripts are executed as they are encountered,
Javascript is the same thing. The browser executes the scripts, and
store whatever it tells it to store in memory. In our example, the
browser now has to parse the <scripttag of the file it received,
having the DOM tree above. When executed, the script makes a requests
to the browser to find the element with an id of "hello". The Browser
returns the <pelement with every nodes it contains (here, it's a
text node "Hello world!"
NOTE : if a script request an element that has not yet been added to
the DOM, the browser will return 'undefined'. This is why you cannot
directly access elements below the <scripttags.
Then, the script tells the browser to add HTML content to this <p>
element. The DOM now becomes :
object:window
...DOMElement:body
.....DOMElement:p{id:"hello"}
.......textElement:Hello world!
.......DOMElement:br
.......textElement:Bye world!
Et voilà!
NOTE : when you use innerHTML in your Javascript, the browser has to
parse the data set to the element. If you can read the value, it's
simply because the browser holds the string that it used to parse the
data when it received the file from the server. It doesn't really use
the data itself for processing beyond the parsing.
In conclusion, the best way to replace data in your page is :
1) the the parent element of your <tableand get it's innerHTML, then
modify it. (Remember, every time you change innerHTML, the browser has
to parse it, so I suggest you use a variable to do what you want, then
reassign the value to the innerHTML.)
2) directly get the elements you want with the DOM methods :
document.getElementById(id) or document.getElementsByTagName(tag) (the
last method returns an array regardless. Be advised!)
3) modify the PHP strings before the script outputs them to the
client.
I hope this was clear enough, and helpful. :)
yanick
