香草JavaScript不会使

I have an html file with a very basic layout (I removed all CSS to make sure it wasn't the problem) and a JavaScript section that draws a very simple pie chart. In the browser it looks fine, and I can't see any errors in the page. Yet wkhtmltopdf won't draw the pie. What am I doing wrong? Or how can I debug this? I am on a Mac, OS version 11.6, wkhtmltopdf 0.12.6 (with patched qt).