Set empty image in JavaScript

Online experiments
1

URL of experiment: https://run.pavlovia.org/Am8302/multipleoutcomes2/html/

Description of the problem: I am trying to set the value of an image to none. This works ok in builder/python but not in JS.

The python code is:
if stimA:
stimL = stimList[int(stimA)-1]
else:
stimL = None

if stimB:
stimR = stimList[int(stimB)-1]
else:
stimR = None

and the JS:

if (stimA!=undefined) {
stimL = stimList[(stimA)-1]
}
else {
stimL = None}

if (stimB!=undefined){
stimR = stimList[(stimB)-1]
}
else{
stimR = None}

I’m also having the issue that the experiment will currently only run on Chrome and freezes on Safari - not sure if this is related.

Thanks,
Alice

2

I have a similar problem - in python empty xlsx cells read as image names give None and as a result - empty image. This is frequently very convenient. However, on pavlovia it does not work - I get unknown resource error (if I remember correctly).

3

I tend to use a small transparent square as a none image but you can try changing None to undefined on the JS side.

4

I was thinking about creating such square, but I’m currently using just size = (0, 0). Its not very elegant but it works. :slight_smile:

6

Here’s an invisible image you can use. I call it transparent.png and it’s native size is 1x1 pixels.

Right-click below here to save:
transparent