jQuery & PHP: Encode & Decode URL

Question

I am passing a string through a URL to another page whenever a link is clicked.

The original a tag and its href are created via a PHP while loop as follows:

<a href=".($row['secondary'] == 'true' ? "secondary_imgs.php?imgId=".$row['imgId']."
    &imgTitle=".$row['imgTitle']."" : "new_arrivals_img/".$row['imgURL']."").">

Note: The a tag does contain other attributes but I removed them for simplicity.

The href is then appended, with the current window dimensions, using the following jQuery function:

$("a[href^='secondary_imgs.php']").click(function(){
    var pageWidth = $(window).width();
    var pageHeight = $(window).height();
    var url = $(this).attr('href');
    var idx = url.indexOf('&pageWidth=');
    if (idx != -1) {
        url = url.substr(0, idx);
    }
    url += '&pageWidth=' + pageWidth + '&pageHeight=' + pageHeight;
    $(this).attr('href', url);
});

My question is, what method(s) of encoding the URL should I use in this case, seeing as it will need to be done with first PHP, then jQuery/JavaScript, and finally decoded via PHP? Or will it need to be done in both PHP and jQuery/JavaScript? The original PHP $row['imgTitle'] will always have at least spaces in it, and so I know it needs to be done then for sure. But seeing as the appended values will always be a variable equalling a number, does that need to be encoded as well?

I know there are several methods of encoding/decoding URLs in each coding language, and my knowledge isn't adequate enough to make the choice.

If someone could also provide an example of how I would perform each step, it would be much appreciated.

Answer 1

You should use urlencode() in PHP to encode URI components.

The equivalent function in javascript is encodeURIComponent() .

PHP will decode parameters encoded like this automatically.

So, in you PHP:

'<a href="..&imgTitle='.urlencode($row['imgTitle'])

And equivalently, in your javascript:

'&someparam=' + encodeURIComponent(someValue)

Answer 2

Why would it need to be done first with PHP? This JS urlencode function is able to be urldecoded from PHP. Encode once, decode once:

function urlencode (str) {
    // URL-encodes string  
    // 
    // version: 1107.2516
    // discuss at: http://phpjs.org/functions/urlencode
    // +   original by: Philip Peterson
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: AJ
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Brett Zamir (http://brett-zamir.me)
    // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: travc
    // +      input by: Brett Zamir (http://brett-zamir.me)
    // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Lars Fischer
    // +      input by: Ratheous
    // +      reimplemented by: Brett Zamir (http://brett-zamir.me)
    // +   bugfixed by: Joris
    // +      reimplemented by: Brett Zamir (http://brett-zamir.me)
    // %          note 1: This reflects PHP 5.3/6.0+ behavior
    // %        note 2: Please be aware that this function expects to encode into UTF-8 encoded strings, as found on
    // %        note 2: pages served as UTF-8
    // *     example 1: urlencode('Kevin van Zonneveld!');
    // *     returns 1: 'Kevin+van+Zonneveld%21'
    // *     example 2: urlencode('http://kevin.vanzonneveld.net/');
    // *     returns 2: 'http%3A%2F%2Fkevin.vanzonneveld.net%2F'
    // *     example 3: urlencode('http://www.google.nl/search?q=php.js&ie=utf-8&oe=utf-8&aq=t&rls=com.ubuntu:en-US:unofficial&client=firefox-a');
    // *     returns 3: 'http%3A%2F%2Fwww.google.nl%2Fsearch%3Fq%3Dphp.js%26ie%3Dutf-8%26oe%3Dutf-8%26aq%3Dt%26rls%3Dcom.ubuntu%3Aen-US%3Aunofficial%26client%3Dfirefox-a'
    str = (str + '').toString();

    // Tilde should be allowed unescaped in future versions of PHP (as reflected below), but if you want to reflect current
    // PHP behavior, you would need to add ".replace(/~/g, '%7E');" to the following.
    return encodeURIComponent(str).replace(/!/g, '%21').replace(/'/g, '%27').replace(/\(/g, '%28').
    replace(/\)/g, '%29').replace(/\*/g, '%2A').replace(/%20/g, '+');
}