How to update date object?

I have the following situation: I have an array of date object and I need to update the date by knowing its index.

var [days, setDays] = createSignal(
  [new Date(768523467), new Date(9837465836256)],
);

var [days, setDays] = createSignal(
  [new Date(768523467), new Date(9837465836256)],
);

So I tried this approach and it doesn't work.

setDays((d) => {
  d[0].setTime(Date.now());
  
  return d;
});

setDays((d) => {
  d[0].setTime(Date.now());
  
  return d;
});

------------------------------------------------------

return (
  <div>
    <For each={days}>
      {(day) => {
        return <div>{`${day}`}</div>;
      }}
    </For>
  </div>
);

return (
  <div>
    <For each={days}>
      {(day) => {
        return <div>{`${day}`}</div>;
      }}
    </For>
  </div>
);

So how can I do that via "mutation" approach? (I don't need immutable way) Whould I use createMutable or createStore for that?

4 Replies

Brendonovich•4mo ago

with a signal you need to update both the array and the date immutably, with a store you'd just need to update the date immutably (as dates aren't tracked by stores) if you do want to use a store then use createStore

FFOP•4mo ago

I got it, but still ther it no point in create new date object. Just want to update object an rerender that. "ther it no point in create new date object" for me.

Brendonovich•4mo ago

you need to create a new Date as solid doesn't track the value inside of a Date to know if it changed, it only tracks the object reference as a more general rule Solid doesn't track inside classes except for some circumstances, only plain arrays and objects

Alex Lohr•4mo ago

Use createTrigger from @solid-primitives/trigger to create a single reactive trigger, then use dirty() whenever you update the Date object using its methods and track() in the functions/memos you use to read from its methods.

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How to update date object?