Javascript object to URL encoded query string converter. Code extracted from jQuery.param() and boiled down to bare metal js. Should handle deep/nested objects and arrays in the same manner as jQuery's ajax functionality.

objectToQueryString.js

    var objectToQueryString = function (a) {
        var prefix, s, add, name, r20, output;
        s = [];
        r20 = /%20/g;
        add = function (key, value) {
            // If value is a function, invoke it and return its value
            value = ( typeof value == 'function' ) ? value() : ( value == null ? "" : value );
            s[ s.length ] = encodeURIComponent(key) + "=" + encodeURIComponent(value);
        };
        if (a instanceof Array) {
            for (name in a) {
                add(name, a[name]);
            }
        } else {
            for (prefix in a) {
                buildParams(prefix, a[ prefix ], add);
            }
        }
        output = s.join("&").replace(r20, "+");
        return output;
    };
    function buildParams(prefix, obj, add) {
        var name, i, l, rbracket;
        rbracket = /\[\]$/;
        if (obj instanceof Array) {
            for (i = 0, l = obj.length; i < l; i++) {
                if (rbracket.test(prefix)) {
                    add(prefix, obj[i]);
                } else {
                    buildParams(prefix + "[" + ( typeof obj[i] === "object" ? i : "" ) + "]", obj[i], add);
                }
            }
        } else if (typeof obj == "object") {
            // Serialize object item.
            for (name in obj) {
                buildParams(prefix + "[" + name + "]", obj[ name ], add);
            }
        } else {
            // Serialize scalar item.
            add(prefix, obj);
        }
    }