serialize.js

/*jslint continue:true*/
/**
 * Adapted from {@link http://www.bulgaria-web-developers.com/projects/javascript/serialize/}
 * Changes:
 *     Ensures proper URL encoding of name as well as value
 *     Preserves element order
 *     XHTML and JSLint-friendly
 *     Disallows disabled form elements and reset buttons as per HTML4 [successful controls]{@link http://www.w3.org/TR/html401/interact/forms.html#h-17.13.2}
 *         (as used in jQuery). Note: This does not serialize <object>
 *         elements (even those without a declare attribute) or
 *         <input type="file" />, as per jQuery, though it does serialize
 *         the <button>'s (which are potential HTML4 successful controls) unlike jQuery
 * @license MIT/GPL
*/
function serialize (form) {
    'use strict';
    var i, j, len, jLen, formElement, q = [];
    function urlencode (str) {
        // http://kevin.vanzonneveld.net
        // 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, '+');
    }
    function addNameValue(name, value) {
        q.push(urlencode(name) + '=' + urlencode(value));
    }
    if (!form || !form.nodeName || form.nodeName.toLowerCase() !== 'form') {
        throw 'You must supply a form element';
    }
    for (i = 0, len = form.elements.length; i < len; i++) {
        formElement = form.elements[i];
        if (formElement.name === '' || formElement.disabled) {
            continue;
        }
        switch (formElement.nodeName.toLowerCase()) {
        case 'input':
            switch (formElement.type) {
            case 'text':
            case 'hidden':
            case 'password':
            case 'button': // Not submitted when submitting form manually, though jQuery does serialize this and it can be an HTML4 successful control
            case 'submit':
                addNameValue(formElement.name, formElement.value);
                break;
            case 'checkbox':
            case 'radio':
                if (formElement.checked) {
                    addNameValue(formElement.name, formElement.value);
                }
                break;
            case 'file':
                // addNameValue(formElement.name, formElement.value); // Will work and part of HTML4 "successful controls", but not used in jQuery
                break;
            case 'reset':
                break;
            }
            break;
        case 'textarea':
            addNameValue(formElement.name, formElement.value);
            break;
        case 'select':
            switch (formElement.type) {
            case 'select-one':
                addNameValue(formElement.name, formElement.value);
                break;
            case 'select-multiple':
                for (j = 0, jLen = formElement.options.length; j < jLen; j++) {
                    if (formElement.options[j].selected) {
                        addNameValue(formElement.name, formElement.options[j].value);
                    }
                }
                break;
            }
            break;
        case 'button': // jQuery does not submit these, though it is an HTML4 successful control
            switch (formElement.type) {
            case 'reset':
            case 'submit':
            case 'button':
                addNameValue(formElement.name, formElement.value);
                break;
            }
            break;
        }
    }
    return q.join('&');
}

Could you add support for email, number etc.?

Here's how I did it: http://pastebin.com/8Sna0wnK

hello, select-multiple don't work ? this is my version

                    case 'select-multiple':
                        q[form.elements[i].name] = [];
                        for (j = form.elements[i].options.length - 1; j >= 0; j = j - 1) {
                            if (form.elements[i].options[j].selected) {
                                q[form.elements[i].name].push(form.elements[i].options[j].value);
                            }
                        }
                        break; 

Sorry hadn't seen either of these comments previously. I believe I moved this to https://github.com/brettz9/form-serialization/blob/master/src/index.js which does have some form of select-multiple support.

My work on this predated FormData, so I don't know if that might do the trick these days.