For me, the answer was I don't want the button to send the form at all, and this helped me:

https://stackoverflow.com/a/3315016/5057078

Text of the answer:

The default value for the type attribute of button elements is "submit". Set it to type="button" to produce a button that doesn't submit the form.

<button type="button">Submit</button>

In the words of the HTML Standard: "Does nothing."