How can I load html in tasklist?

If I want my tasklist to load specific html, how could I achieve?
Something like some processes need to load personal data in every task, so I need put the same data in lot of tasks.

I know it could write html in javascript, but I only know use innerHTML function and set a button to implement it.
Don’t know how to load it without a button trigger, and I don’t want write innerHTML in every html.

Please help.
Much appreciate!