Error: Backspace exiting experiment prematurely

Online experiments
1

URL of experiment:

Description of the problem:

Some participants reported being booted from the experiment after pressing the backspace during a text input portion. Everyone has reported using the Firefox browser. However, I have not been able to replicate this experience on my own, so I don’t know if there is a specific error message that accompanies the premature experiment closure. Has anyone else dealt with this issue? Any help would be greatly appreciated!

2

Is there an error caused by trying to delete something from an empty string? You could force backspace to only work if the current response has at least one letter.

3

Thank you for the lightning fast reply!

I am not sure what exactly is causing the error. I tried the backspace without any letters in the response. Nothing happened. The experiment continued just fine. If this is an occasional issue, I would like to add it in in case this affects some people!

Here is the code under Each Frame in the routine that asks for a text response:

let theseKeys = psychoJS.eventManager.getKeys();
if (theseKeys.length > 0) { // at least one key was pressed
textAdd = theseKeys[theseKeys.length-1];
}

if (textAdd === ‘return’) {
textAdd = ‘’; // Add nothing
continueRoutine = false; // End routine (if that is what you want)
} else if (textAdd === ‘space’) {
textAdd = ’ '; // Add a space
} else if (textAdd === ‘backspace’) {
text_20.text = text_20.text.slice(0, -1);
textAdd = undefined;
} else if ([‘lshift’, ‘rshift’].includes(textAdd)) {
modify = true;
} else if (textAdd !== undefined) {
if (modify) {
text_20.text = text_20.text + textAdd.toUpperCase();
modify = false;
} else {
text_20.text = text_20.text + textAdd
}
textAdd = undefined;
}

How would I add code to force backspace into working only if there is at least one letter?

Thanks again so much for the help!

4

Try moving the } from the fourth line of your code to the bottom. You only need to check textAdd if there’s a key press.

5

Great! That includes everything in the first if statement. Thank you very much