James Aylett: Accessibility Advent: strip leading spaces

Published at
Monday 3rd December, 2012

(Throughout Advent I’m sharing some hints as to how web developers can make my life as a speech recognition user easier.)

There are any number of strange effects of using speech recognition to drive a computer, but the one that affects almost everything I do – and that I forget most often that I have to take account off – is leading spaces. Dragon doesn’t always notice when you’ve moved between input elements, and when it doesn’t it assumes any dictation continues the previous sentence. This results in a leading space in the new input.

You can imagine all sorts of situations where this is a pain, but the one that annoys me most is when I have to put in credit card or banking details. (It can also be a problem with CAPTCHA, although usually less than figuring out what the messed up letters are in the first place.)

I’ll note in passing here that, yes, this is a software problem at my end: it should be possible for Dragon to get this right. Indeed if I remember correctly, Dragon Naturally Speaking on Windows doesn’t have this problem, and for that matter if I used Safari on Mac there are commands that can help navigate text inputs while telling Dragon what’s going on. I dislike Safari sufficiently that the alternative would be to go back to Windows, where Dragon Naturally Speaking provides better integration with Internet Explorer.

The leading space issue doesn’t just crop up with web forms – Glee Box itself suffers from it, for one, and sometimes the 1Password unlock screen gets a rogue space as well. I can say “no space” before a word to prevent the leading space, but I don’t always remember. I’d love it if web forms just stripped leading spaces so this never bit me, but it’s particularly annoying when it interacts with naïve validation.

Leading spaces should not be considered invalid in numeric fields. Most string to number conversion functions will happily skip them, and so should your validator, be it a regular expression or something more esoteric. This is equally true whether your validation runs on the backend or front-end (and, sidebar, it should run on both); if the latter then there’s another problem, which banking sites are particularly prone to run foul of.

Long numbers are hard to type in accurately (they’re easier to dictate, as it happens). One way of making things easier is to split them into shorter sequences – for instance, your credit card probably has four groups of four digits on the front instead of just one sixteen digit string. This is fine.

Similarly, to allow people to verify that they typed a number in correctly, some sites use multiple input boxes, building the single number in code somewhere. I haven’t seen this often with credit cards, but it gets used for software registration numbers a lot, and some banks split up the authentication codes coming in from PIN-based token generators, such as Barclays’ PINsentry.

As a web developer you see a requirement for two boxes each taking four digits, so you set the maximum length (maxlength) of each input to four.

[1234] [5678]

Then I come along with my leading space problem and this happens:

[ 123] [5678]

Actually it’s usually worse than that, because you’re clever so you advance the focus once there are four characters in the first input:

[ 123] [4567]

Then some other clever developer adds client-side validation to the form. One of two things happens, depending on where the focus is left. Most commonly, the focus seems to end up on a help link explaining what went wrong:

[ 123] [] ERROR!

If I’m lucky I can then tab back to the first input and try again. It’s around this point that I want to punch someone. (For reasons I don’t understand, inputting numbers in this stop-start staccato fashion is considerably more stressful than dictating prose and then correcting it.)

So what should happen? With client side validation, killed the leading space when it appears. Without (and this is going to upset some people), set the input maximum length to one more than you’re looking for (five, in this case) – and then deal with this properly in the backend so an input like the following still works:

[12345] [678]

Using client-side validation here is a Very Good Thing, clearly.

But wait, it gets worse. Say you read the above and decided one big input is better (as most people do for credit card numbers, for instance). You allow Allow the slightly larger input maximum length, strip any leading space, and then reuse that code when building an e-banking setup system, where an authentication code gets mailed through the post to confirm the user is who they say they are. You parameterize your widget based on code length. Two years later someone rolls it out for codes the same length as US phone numbers. Dragon helpfully formats my code as a phone number:


So you should probably strip internal hyphens, and make the input maximum length even longer – in fact, I’m beginning to wonder if exact input maximum lengths are ever useful.