What, other than redraw, causes a component's view function to be called (endlessly)?

[EverettMcKay]

I just discovered that for one of my components, the view function is called endlessly. I discovered this by accident by console logging, but otherwise the component is behaving as it should. I have confirmed that this is not normal by doing the same in other components.

What is causing this? I confirmed that m.redraw() is not being called and v.state is modified only in event handlers. What else causes redraws?

[dead-claudia]

The only way Mithril redraws is if one of the following occurs:

1. You invoke m.render directly (which sidesteps the autoredraw mechanism)
2. You invoke m.redraw()
3. You invoke m.redraw.sync()
4. A Mithril-managed event handler is invoked and returns a value other than false

There are ways to cause render loops without explicit renders, though. For example, you could do it with focus and blur events:

• On some element A, you add an onfocus handler that sets a flag to add another element B, and an onblur to remove it.
• You set up code such that if there's no focused element, that element A is focused.
• Element B has code to enforce focus when present.
• You notice that it doesn't work at first, so you decide to hack in a fix to also restore focus whenever element B is removed.

With the above, you'd be stuck in this loop:

1. No element, element A adds focus.
2. Element A's onfocus called, element B added.
3. Element B takes focus, element A's onblur handler called.
4. Element B removed, no focus. Workaround re-adds focus to element A.
5. Repeat from step 2.

I'd need to see code to not just take shots in the dark, though.