Load text from a .txt file and display in jsPsychHtmlButtonResponse

I want to use jsPsychHtmlButtonResponse to display a .txt-file from a local folder on my computer.
The reproducible code below does not work, while a very similar adaptation works for the display of images with jsPsychImageButtonResponse.

Does not work:

var text_display = {
type: jsPsychHtmlButtonResponse,
stimulus: text_files/test.txt,
choices: [“Ready”],
};

Works:

var image_display = {
type: jsPsychImageButtonResponse,
stimulus: images_files/test.png,
choices: [“Ready”],
};

Do you have any suggestions how to handle this problem?