HTML5 text boxs for numbers and email addresses

In HTML5 there are a few new types of text box available that can help with mobile development. For example, on mobile devices it can be useful to have the on-screen keyboard be defaulted to display a specific configuration when it is displayed, such as the numeric keypad.

Not all browsers support these new text box types at the moment, but it seems that if the browser doesn’t understand the type assigned to an input element it renders it as a textbox anyway.

Regular Textbox

By regular text box I mean something rendered with something like the following HTML:

<input type="text />

Normally, I use SwiftKey, but for this demonstration I’ve switched to the default Android keyboard.

Keyboard for regular text box

Numeric Textbox

You can set the default keypad to numeric by specifying an input like this:

<input type="number" />

Numeric input displaying numeric keypad

Email text box

Finally, there is an email input type that configures the keyboard to display a key for “.com” and a specific key for the “@” as well as dedicated keys for the “-” and “_”  next to the space bar (at least that’s how the default Android keyboard configures itself in this mode – YMMV). The input element looks like this:

<input type="email" />

Email keyboard


If you want to try this out for yourself, there is an example available.

Opting out of Google Instant Browsing

I recently wrote about a new feature of Google Chrome called Instant Browsing. You can turn it on or off Basic tab of the  Options page in Chrome.

If you are a web site owner/administrator and are concerned about the impact it might have on your web server to have a deluge of requests going to your server that the end user is probably not really interested in, or having a number of requests going to your server that result in a 404 resource not found because the half formed URL in the “omnibox” does not actually resolve to a real page then you can opt out.

For folks running ASP.NET (both WebForms and MVC) I’ve created a simple HTTP Module that will opt your site out if it encounters requests from Chromes’ Instant Browsing.

You can download the Module here: Instant Browsing HTTP Module V1. And to activate it in your application you need to add the DLL file as a reference to your application and then add the bolded line to your web.config.

   <add name="InstantBrowsingOptOut" type="InstantBrowsing.InstantBrowsingOptOut, InstantBrowsing"/>


The Code

If you prefer, you can add the following source to your application and compile it yourself.

using System;
using System.Collections.Specialized;
using System.Web;

namespace InstantBrowsing
    public class InstantBrowsingOptOut : IHttpModule
        public void Dispose()
            // Nothing to dispose. Required by IHttpModule

        public void Init(HttpApplication context)
            context.BeginRequest += new EventHandler(BeginRequest);

        void BeginRequest(object sender, EventArgs e)
            HttpApplication application = (HttpApplication)sender;

            string headerValue = GetPurposeHeaderValue(application.Request);
            if (HeaderValueDoesntExist(headerValue))

            if (PreviewMode(headerValue))

        private bool PreviewMode(string value)
            return value.ToLowerInvariant().Contains("preview");

        private bool HeaderValueDoesntExist(string value)
            return string.IsNullOrEmpty(value);

        private string GetPurposeHeaderValue(HttpRequest request)
            NameValueCollection headers = request.Headers;
            return headers["X-Purpose"];

        private void Issue403Forbidden(HttpResponse response)
            response.StatusCode = 403;

And to activate it in your application you need to add the bolded line to your web.config.

   <add name="InstantBrowsingOptOut" type="InstantBrowsing.InstantBrowsingOptOut, InstantBrowsing"/>

Note that the second “InstantBrowsing” in the type attribute is the assembly, so if you’ve put it in an assembly with a different name you’ll need to change the type attribute to reflect that.

Google Instant Browsing

What is Instant Browsing?

Google Chrome 12 comes with a some features, including support for Google’s Instant Searching and Instant Browsing via the address bar (or “omnibar” as they call it). This means that as you type your query or URL it will be sent off with almost every character press constantly updating the page underneath.

If you have this version of Chrome and don’t currently see what I’m talking about you can go into the Options and in the Basic tab look for the Search options. Make sure that “Enable Instant for faster searching and browsing” is turned on.

Now you will see what happens as you type URLs into the “omnibox” (the address bar). If you additionally run Fiddler you’ll see how many requests are being made in the background.

For example, if I start typing my blog URL, by the time I’ve finished typing my forename it has already concluded that I want to see my blog and I can see in fiddler it has already made the request to and my blog appears while I’m still typing.

What’s going on?

If I continue on, say I’m looking for something on SQL, I can see this progression in Fiddler of all the requests that get sent to my blog. (I’ve removed some of the other requests that are unimportant for this example)

As you can see, sometimes I can type quite quickly and it has to play catch up. Sometimes, I slow enough that the blog responds with a 301 (the server does its best to guess what you want, treating an invalid URL as a sort of search term and redirecting you to its best guess) or a 404 if it can’t resolve the URL.

Try this on the BBC News website – As you type URLs you get tons of 404 pages back as the intermediate (non-functioning urls) get responded to!

As you can see from the image of Fiddler above there are some requests missing, some were the browser pulling down CSS and images from my blog, others were request off to Google looking to augment the instant browsing feature.

These calls to augment the Instant Browsing feature are all being sent off to (I suspect that in each locale there will be a different set of URLs that are able to best match queries in that area). It consists of a GET request with the query in it. The query being what you have typed in the “omnibox”. For example:

This results in some JSON being returned. If you are typing URLs it doesn’t appear to be that useful. The above returned the following to me:


It becomes much more interesting when a search term is used rather than a URL.

By typing simple “rupert” in the omnibox the result from the request is:

["rupert",["rupert murdoch","rupert grint","rupert everett"],["","",""],[],

Chrome then auto-suggests “rupert murdoch” as the primary completion with the drop down also suggesting “rupert grint” and “rupert everett”

Incidentally, you don’t get Instant Search or Instant Browsing while in Chrome’s Incognito Windows event if it is turned on.

Can anybody say DDoS?

While the expansion of Google’s Instant Search feature into Chrome is fantastic, my first thought when I saw Instant Browsing was that it could be used as a way to mount a DDoS (Distributed Denial of Service) attack on a website especially those that may be running on less robust hosting plans. It is okay for Google to inundate their own web properties from their browser but what about other site owners?

If a web site is not expecting the deluge of requests coming from Chrome browsers then it may be saturated dealing with requests that the user isn’t likely to be all that interested in anyway, especially if intermediate results are bringing back 404 responses (or worse 500 responses if the server breaks badly on bad URLs).

Google have thought of this and there is a way to tell Chrome to stop sending requests that you don’t want. If you read the Chrome FAQ for web developers, you’ll see there is a section opting out of Instant URL Loading. In short, you detect a request header that Chrome has inserted into the request and if you want to opt out return a HTTP 403 status code.  This will then have Chrome blacklist that website for the remainder of the user’s session. This means that if the user comes back another day there will still be that initial hit, giving the web site administrators a chance to opt back in.

An instant browsing request looks like this:

Connection: keep-alive
X-Purpose: : preview
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.112 Safari/534.30
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-GB,en-US;q=0.8,en;q=0.6
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3

The important part is the X-Purpose header. This is what tells the server that the browser is rendering the page as part of the Instant Browsing feature.

Note: The FAQ states that the header is “X-Purpose: preview” but fiddler shows an extra colon in there (see above). If you are attempting to detect the mode of the browser this may become important to the way you detect it.