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Question

cancel load page in javascript

Answer 1

A:

Browsers won't allow you to make a cross domain request.

See more details here, here and here.

BrunoLM 2010-10-13 16:30:49

Answer 2

A:

Has to be from the same domain or the domain has to use CORS for safari 4 and Fx 3.5+
you need to return false on the click
you need to use the url.href
you need to alert before you redirect

function check(link){ /* ONLY works from same domain OR if the target implemented CORS! */

    xmlHttp.open("GET", link.href, true);  

    xmlHttp.onreadystatechange=function(){

    if(xmlHttp.readyState==4){
        if (xmlHttp.status==200) 
        {
            alert("Page  Available");
        }
        else 
        {
            window.location.href= "http://www.hello.com";
        }
    }
}

xmlHttp.send(null);
return false; // imperative
}
</script>

</head>
<body>
<a href="http://www.example.com" onclick="return check(this)">Click this Link</a>

mplungjan 2010-10-13 16:32:23

And I tried to post some script and SO puked all over it :(

mplungjan 2010-10-13 16:33:20

@mplugjan: Indent it correcly, so SO knows it's code.

poke 2010-10-13 16:35:12

i tried return false;

anish 2010-10-13 16:46:55

i tried.but it doesn't work

anish 2010-10-13 16:47:18

@anish: That isn't the correct code; it's broken.

poke 2010-10-13 17:08:37

Finally got something posted that looks like code. SO was NOT happy and I indented and indented

mplungjan 2010-10-13 19:01:01

Answer 3

A:

Your onclick attribute should contain:

 check(this.href);

andrewmu 2010-10-13 16:32:59

but i get the url in a funtion.i checked with an alert

anish 2010-10-13 16:48:22

You saw the URL printed, but that's because the `a` element's `toString()` method returns the URL, not because it *is* the URL

andrewmu 2010-10-13 16:59:53

Answer 4

+2 A:

Okay, multiple points:

onclick="check(this)" doesn't pass the URL to the check function but a reference to the the link object. So if you want to pass the URL, you have to reference the href attribute.
You shouldn't set window.location.href when you want to output something else afterwards. Setting the current location can make the browser change the page directly, so the alert probably won't change.
Why the if where you change the location to google each time?
You can only abort the processing of link click, by returning false in the event handler.
AJAX calls are, as the first parameter says, asynchronous. But as you abort the page loading already (by clicking on the link), the AJAX call gets aborted.
You can't return false from inside of the AJAX event handler (onreadystatechange) to stop the processing of the link. By the time you get there, the link is already processed.
That, what you are trying, is not really good. It should be up to the user to check if a page exists or not. It would be very wrong to redirect him to some other page (here: google) just because the link didn't work; at least I would be very confused. Also by checking that with AJAX, you make the user load the page twice, which is bad as well.

poke 2010-10-13 16:34:20

onclick="check(this)".it passes the url

anish 2010-10-13 16:48:58

@anish: No, it passes a reference to the DOM element. It just equals to the URL when casted as string. Check with `typeof( url )` in the `check` function.

poke 2010-10-13 17:01:59

Answer 5

A:

You are not passing the url. You are passing the DOM element of the link. You need to use url.href or in jQuery you need to use $(this).attr('href').

Also the JavaScript is not preventing the link from being followed. You need to have the function return false, and have no errors before it does or you can use jQuery and event.preventDefault().

Finally even if you did all because of the same origin policy it will only work for links on the same domain you're on. Here is a link to a jQuery version of your code.

Adam 2010-10-13 16:37:20

Answer 6

A:

Ok you are nearly there. A lot of useful comments so far. But it might be better to redirect from the server not from the client. I personally would pass parameter to a fucntion on your server (your server script's url) (capturing the href using jquery) to a function on your server, then use that passed url to do a (head) check and redirect them via the server if it exists. If the site doesn't exist, then don't redirect and just send JSON back to the client and let them know the site doesn't exist.

dryprogrammers 2010-10-13 16:40:54

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cancel load page in javascript

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