Question

First time trying to use JSON.
Here is my checklink.php :

function url_exists($url) {
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_NOBODY, true);
    curl_exec($ch);
    $retcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    // $retcode > 400 -> not found, $retcode = 200, found.
    if ($retcode == 400){
    return "false";
    }else{
    return "true";
    }
    curl_close($ch);
}
$response = array( 
  'location' => $location, 
  'status' => $status 
);
$rr = url_exists($response['location']);
echo json_encode( $rr );

JS part :

function UrlExistsNew(url, callback) {
  $.getJSON('checklink.php', { location: url }, function ( data ) {
  callback.apply( null, data.status );
});
}
...
UrlExistsNew($(this).val(), function(status){
        if(status === "false") $(element).css('background-color','#FC0');
      }); 
...

It seems the php page is not returning result to json query.

Edit : Note that I forgot to install curl and enable it in my server. I Hope no one miss this.

Answer 1

OK, After doing test and trials for 8 hours. I finally got this working. Thanks a lot to Vytautas. He teached me a lot. Mostly how to debug.

For anyone who wants to check broken links using JSON + PHP + CURL :

1. First of all, Check if you have curl installed and enabled in your server.
2. Those who don’t understand curl : If there is a response from your url, there will be a status code (like 200 or 404). If the url entered is blank, invalid or anything like that, It will return status code 0
3. If you can’t get the proper response from php page, use FireBug (Console Tab) to check the headers and responses. Also use breakpoint to see if variables are passing correctly.

Here is the php code :

function url_exists($url) {
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_NOBODY, true);

    if(curl_exec($ch) === false) // These 2 line here are for debugging.
        die('Curl error: ' . curl_error($ch));

    $retcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);
    return $retcode;
}
$response = array(
  'status' => url_exists($_GET['location'])
);
echo json_encode($response)

I was doing 2 thing wrong in php. I should have used $_GET['location'] instead of $location And the other was $response instead of using a second variable.

And the js function :

function UrlExistsNew(url, callback) {
  $.getJSON('checklink.php', { location: url }, function ( data ) {
  callback.call( null, data.status );
});
}

Another thing I was doing wrong in js was passing callback to the function. I should have used callback.call instead of callback.apply

Simple usage :

UrlExistsNew($(this).val(), function(status){
        if(status === 404) $(element).css('background-color','#FC0');
      });