"&" is not a good join char!

erme2 · April 13th, 2007, 11:59 AM

Hi,
On chapter 2, in the first box code you wrote:

return aParams.join("&");

I think "&" is not a good char to make join()... When there's a "&" in a element value you will have an incoplete post!

How can I fix this?

Thanks...

jmcpeak · April 13th, 2007, 02:17 PM

Howdy, erme2.

Joining the elements of the array with "&" is a requirement for HTTP communication. The string returned by aParams.join() is the request body sent to the server, and "&" has to separate the key/value pairs. No other character can be used.

You do have a point that problems can arise if "&" is in an element of the array. However, the code in Chapter 2 makes this a non-issue by encoding both the key and the value with the encodeURIComponent() method. Here is the getRequestBody() function as detailed in Chapter 2:

Code:

function getRequestBody(oForm) {
    var aParams = new Array();

    for (var i=0 ; i < oForm.elements.length; i++) {
        var sParam = encodeURIComponent(oForm.elements[i].name);
        sParam += "=";
        sParam += encodeURIComponent(oForm.elements[i].value);
        aParams.push(sParam);
    } 

    return aParams.join("&");
}

Any "&" that is passed to encodeURIComponent() ends up as %26, effectively dodging any issue that would otherwise arise with "&".

------------------------
Jeremy McPeak
Author of:
Professional Ajax, 2nd Edition
Beginning JavaScript, 3rd Edition

http://www.wdonline.com

erme2 · April 15th, 2007, 12:43 PM

"Any "&" that is passed to encodeURIComponent() ends up as %26, effectively dodging any issue that would otherwise arise with "&"."

You are right, I was so tired...
Really my problems started whit checkbox and radio elements, I solved with a switch case but writing the default case I omitted some code...

Thanks for your help I solved so...
(it works!)

function getRequestBody(funct_form) {
    var aParams = new Array();
    for (i=0; i<funct_form.elements.length; i++) {
        switch (funct_form.elements[i].type) {
            case 'radio':
                if (funct_form.elements[i].value=='S' && funct_form.elements[i].checked) { var sParam = funct_form.elements[i].name+"=S"; aParams.push(sParam); }
                else { var sParam = funct_form.elements[i].name+"=N"; aParams.push(sParam); }
                break;
            case 'checkbox':
                if (funct_form.elements[i].checked==true) { var sParam = funct_form.elements[i].name+"="+funct_form.elements[i].value; aParams.push(sParam); }
                break;
            default:
                var sParam = encodeURIComponent(funct_form.elements[i].name);
                sParam += "=";
                sParam += encodeURIComponent(funct_form.elements[i].value);
                aParams.push(sParam);
        }
    }
    return aParams.join("&");
}