ajax browser check

pedroz

<script language="javascript" type="text/javascript">
<!-- 
//Browser Support Code
function ajaxFunction(){
	var ajaxRequest;  // The variable that makes Ajax possible!

try{
	// Opera 8.0+, Firefox, Safari
	ajaxRequest = new XMLHttpRequest();
} catch (e){
	// Internet Explorer Browsers
	try{
		ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
	} catch (e) {
		try{
			ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
		} catch (e){
			// Something went wrong
			alert("Your browser broke!");
			return false;
		}
	}
}
}
//-->
</script>

I found the code below to check if the browser supports Ajax [but it is javascript]

I would like to know if there is any PHP script doing the checking above and displaying a yes/no.

example:
Internet explorer 4.0
http:/myhost/check.php
output: ajax NOT supported

Internet explorer 7.0
http:/myhost/check.php
output: ajax supported

Thanks

MarkR

This is a client-side check which needs to be done in Javascript.

However, you could post the result back into PHP by putting a value in a hidden field.

Alternatively, do a Javascript redirect if the check succeeds. You could then have a "Refresh" header which redirects them to another page automatically if the check fails (or JS is not available).

Mark

scrupul0us

not having used AJAX but understanding that it works with JS your first measure should be to detect if JS is working

put some PHP code within some noscript tags and see how that works for you

<noscript>
<?php echo "NO SCRIPT"; ?>
</noscript>

that will output "NO SCRIPT" when JS is disabled... thats my general tactic for detecting JS with php

pedroz

Excellent 🙂

scrupul0us

quite versatile i think since its a clean way of dealing with non-js users

on the same token... there is a built-in function in php to detect some basic browser stuff (including JS)

http://www.php.net/manual/en/function.get-browser.php

example:


$browser = get_browser(null, true);

if ($browser['javascript'] == "1")
{
//javascript is enabled
}
else
{
//javascript is disabled or not supported
}

the noscript tags are useful if you just have a little inline processing todo... but if u need total control of a page within the php structure as determined by some of those variables then by all means use the function

its PHP 3->5 friendly as well!

MarkR

Unfortunately there's no way of determining on the server-side, whether Javascript is supported (no, get_browser does not work, as it won't detect if Javascript is supported but disabled, nor will it work if a User-agent header isn't sent.).

So you'll have to make a client-side check.

I recommend you do this:

Create a start page which just checks for compatibility, and if it's compatible, redirect to the page where the AJAX etc, is used
Use a meta refresh (or HTTP Refresh header) to redirect to another page after 10 seconds or something, if the Javascript fails to redirect - this page can be a "downgrade" version or an error message describing the requirements (e.g. enable Javascript)

Mark

scrupul0us

well in that case id use the no script tags to set a variable if JS is disabled or not supported and then redirect

MarkR

Unfortunately there is no obvious way to "Set a variable" or "Redirect" using "noscript" elements.

Noscript only works for HTML. You can't put Javascript inside noscript (obviously), nor can you set variables or redirect in plain HTML with script disabled.

I preferred by refresh idea.

Mark

scrupul0us

MarkR wrote:
You can't put Javascript inside noscript (obviously), nor can you set variables or redirect in plain HTML with script disabled.

thats my point... put w/e you want non-js users to see within the noscript tags

MarkR

scrupul0us wrote:
thats my point... put w/e you want non-js users to see within the noscript tags

However, you can neither "set variables" (whatever that means in this context) or redirect them with plain HTML inside a noscript element.

You could write a message and put a link in for them I suppose.

I prefer to use Refresh:, as that will redirect them even if JS is off.

Also, you should cater for the situation where JS is available but crashes out for some reason and fails (e.g. a browser you have not tested with because it doesn't exist yet).

Mark