Update data from outside the component

Hi, i searched a lot about this, but i cant’ figure out.
So, i have a page (no webpack used), and i loop over a variable to create a list:
${testList.map((test) => $h <li>${test}</li> )}

Now, how to update “testList” variable and re-render the component without reload the page? i need to do this from OUTSIDE the component, (ex: from the browser debug console).
Thanks, it’s really urgent.