Background image for certain trials

[einGlasRotwein]

Hello everyone,

how do I set background image for a certain trial type, say, only for the fixation screen. I was able to set a background image for the whole task based on this discussion. I am also able to change the background colour, e.g. during on_finish() of the previous trial using document.body.style.background = '#000000'; or, alternatively:

disp = document.querySelector('.jspsych-display-element');
disp.style.background = '#000000';

However, this does not work for images. If I use the image path (document.body.style.backgroundImage = "./images/example.png";), nothing happens at all. If I use url() on the path (which works fine if I use it as style in the body like in the discussion linked above; document.body.style.backgroundImage = url("./images/example.png");), I get an error that the url is not defined.

How do I change the background image dynamically?

Thank you in advance
Juli

[becky-gilbert]

Hi Juli! Your second solution is correct, you just need to put the url() in quotes:

document.body.style.backgroundImage = 'url("./images/example.png")';

See here for the docs on setting style.backgroundImage. I hope that helps!