At 09:59 AM 7/30/2006, Jochen Kaechelin wrote:
How can I call a JavaScript inside php?
You can't literally call client-side JavaScript from server-side PHP
because they're executing at different times and in different
computers. PHP executes on the server then downloads the page to the
browser, then JavaScript executes in the browser.
What you can do is to write your PHP script so that it generates your
JavaScript code as part of the page download, set to execute
automatically when the page downloads. The JavaScript can either be
inline in the HTML page itself or linked to the HTML page with a
script tag and a SRC attribute that produces the desired JavaScript
on the fly, e.g.:
echo <<< hdJS
<script src="myJavaScriptGenerator.php?param=value"
type="text/javascript"></script>
hdJS;
If your JavaScript is static -- already written, not needing
modification -- you can simply link it to your PHP-generated HTML
page as usual:
echo <<< hdJS
<script src="myJavaScript.js" type="text/javascript"></script>
hdJS;
Another variation involves a static JS script that's fed
dynamically-generated variables by PHP. This isn't a shared variable
space between the two languages but more like a communication channel
between them:
$frog = 'Hello';
$dog = 'world';
echo <<< hdJS
<script type="text/javascript">
var frog = "$frog";
var dog = "$dog";
</script>
<script src="myJavaScript.js" type="text/javascript"></script>
hdJS;
Of course you can generate entire blocks of JavaScript logic with PHP
if need be, but I would suspect that in most cases you'd be better
off feeding a few key variables to a static JS script.
_________________________________________
Most of the time you'll want your JS script to execute after the HTML
finishes downloading, so that JavaScript will be able to find all the
page elements in the DOM. Three ways of doing this are:
1) Use the window.onload method in a linked JavaScript script:
window.onload = jsFunctionName;
function jsFunctionName()
{
...
}
Notice the lack of parentheses in the onload statement. This is
because you want to set window.onload equal to the content of the
function, not execute the function as would occur if you wrote
"window.onload = jsFunctionName();".
The window.onload statement wipes out any pre-existing onload
function. Multiple linked scripts can use this method cooperatively this way:
// save any pre-existing onload function
var uniqueVariableName = window.onload;
// do the following when the page finishes downloading:
window.onload = function()
{
// if there was a pre-existing onload
function, run it now
if (uniqueVariableName) uniqueVariableName();
// run the function
jsFunctionName();
}
// here's the function you want to execute when the page has loaded
function jsFunctionName()
{
...
}
In this example, "uniqueVariableName" is different for each script
that uses it. I usually use the name of the JavaScript file as part
of this variable name to ensure uniqueness.
Multiple onloads can also be implemented using the addEventListener method:
http://developer.mozilla.org/en/docs/DOM:element.addEventListener
2) Use the onLoad attribute in the body tag:
<body onLoad="jsFunctionName();">
...where jsFunctionName() is a function in a linked or inline script.
I don't recommend this method because it mixes HTML with scripting
more than is necessary. The more separate you keep them, the easier
both will be to maintain.
3) Insert the function call in a script statement at the bottom of
the HTML markup:
...
<script type="text/javascript">
jsFunctionName();
</script>
</body>
</html>
Same argument against mixing HTML with scripting, although one could
argue that this constitutes the same degree of mixing that occurs
with the <script src= tag.
Regards,
Paul
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
