Restricting to desktop

[kmoulton]

Hi,

I’ve searched through the forum here and don’t *think* I’ve seen this issue exactly addressed, but forgive me if it is. We want to ensure that only desktop users (or at least not phones) can do our SPR study – or at least to have a way of tracking this. I’ve seen other experiments that have browser/OS checks and so on, but I do not know how that is done and if it would help. Any thoughts/tips?

Thanks

[Jeremy]

Hi,

There’s no bulletproof method to ensure that someone is using a desktop rather than a phone or a tablet, but there are good approximation methods.

One option is to check the width of the screen:

newTrial(
    newFunction( ()=>window.matchMedia("only screen and (max-width: 760px)").matches )
        .test.is(true)
        .success( 
            newText("<p>We're sorry but this experiment requires a wider resolution.</p>"+
                    "<p>Please do not use a modile device to take this experiment.</p>"+
                    "<p>If you are using a desktop browser, make sure to maximize this window.</p>")
                .print()
            ,
            newButton().wait() 
        )
)

Another solution is to use user agent sniffing:

newFunction( ()=>navigator.userAgent.match(/Android|BlackBerry|iPhone|iPad|iPod|Opera Mini|IEMobile/i) )
    .testNot.is(null)

Jeremy

[florians]

Another simple feature that makes it at least very hard (possibly impossible, not sure) to proceed in an experiment with a device without a physical keyboard is to just include a ‘press space to continue’ step, using newKey(). Without a text input field, there generally is no straightforward way (if any, haven’t found one) to bring up the virtual keyboard on a phone or iPad, which means you cannot continue. (I learned this by accident in a recent study where I was leaving tablet use as an option on Prolific, and had lots of people falter precisely for this reason.) Thinking on it, I wonder whether self-paced reading would work on devices without a keyboard to begin with – is there any way to proceed within a sentence without pressing a keyboard key?

[kmoulton]

thanks!!
As for spr even being possible on a phone: i found that iphones (n=2 types) would display a “Next” button to progress through the regions (but yes – as you say – I get stalled at a “press any key to continue” screen). I was just surprise that this Next button appears on the phone when on a desktop one just presses the spacebar to proceed. This is native Ibex.

[Jeremy]

Alex Drummond wrote this in utils.js: var isIPhone = navigator.userAgent.match(/iPhone/i) || navigator.userAgent.match(/iPod/i);

And the code of DashedSentence contains a conditional on isIPhone to print the “Next” button. I guess the longer term idea was to expand the check to any mobile browser (remember that Alex started writing ibex in the early 2010s)

Jeremy

[murphybeck]

User Agent detection is not a recommended technique for modern web apps. You can use JavaScript window.matchMedia() method to detect a mobile device based on the CSS media query.

if (window.matchMedia("(max-width: 767px)").matches)
{
// The viewport is less than 768 pixels wide
document.write("This is a mobile device.");
}

Another approach would be a responsive media query. You could presume that a mobile phone has a screen size greater than x and less than y.

For example:

@media only screen and (min-width: 320px) and (max-width: 600px) {}

You may also use navigator.userAgentData.mobile .

const isMobile = navigator.userAgentData.mobile;

[Jeremy]

Thank you for the detailed updates

Unfortunately navigator.userAgentData.mobile is not currently supported by Firefox and Safari according to MDN Web Docs

Checking the min/max width of the page is indeed a minimally intrusive proxy, although it doesn’t really check whether the participant is using a mobile device—admittedly, user agent sniffing also has its limits, as it can be tweaked by the client

Jeremy

[Author]

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