how can I use createEffect so it doesn't rerun when certain signals change

my code: https://github.com/nikitavoloboev/test/blob/main/solid-start/src/routes/snake.tsx

GitHub

test/snake.tsx at main · nikitavoloboev/test

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15 Replies

nikivi•2y ago

@lexlohr shared this code

You want createEffect(on(event, (ev) => { /* ev is the content of event() */  }))

You want createEffect(on(event, (ev) => { /* ev is the content of event() */  }))

but I am confused still how to apply it

nikivi•2y ago

https://www.solidjs.com/docs/latest/api#createeffect

SolidJS

Solid is a purely reactive library. It was designed from the ground up with a reactive core. It's influenced by reactive principles developed by previous libraries.

nikivi•2y ago

i checked docs for createEffect api

  createEffect(
    on(event, (ev) => {
      if (event()) {
        switch (event().key) {
          case "w":
            moveSnake(grid(), setGrid, "up", snake(), setSnake)
            break
          case "a":
            moveSnake(grid(), setGrid, "left", snake(), setSnake)
            break
          case "s":
            moveSnake(grid(), setGrid, "down", snake(), setSnake)
            break
          case "d":
            moveSnake(grid(), setGrid, "right", snake(), setSnake)
            break
          default:
            break
        }
      }
    })
  )

  createEffect(
    on(event, (ev) => {
      if (event()) {
        switch (event().key) {
          case "w":
            moveSnake(grid(), setGrid, "up", snake(), setSnake)
            break
          case "a":
            moveSnake(grid(), setGrid, "left", snake(), setSnake)
            break
          case "s":
            moveSnake(grid(), setGrid, "down", snake(), setSnake)
            break
          case "d":
            moveSnake(grid(), setGrid, "right", snake(), setSnake)
            break
          default:
            break
        }
      }
    })
  )

so I have this now

Alex Lohr•2y ago

You can use ev instead of event()

nikivi•2y ago

ok I think it works thank you got some bugs with logic but at least it doesn't rerun many times kind of shame that on is not documented as part of createEffect it seems its a common case at least in react to attach effects to only certain values

Alex Lohr•2y ago

I would also refactor this:

const directionKeys = {
  w: "up",
  a: "left",
  s: "down",
  d: "right"
}

createEffect(on(event, ev => {
  const direction = directionKeys[ev.key];
  if (direction) {
    moveSnake(grid(), setGrid, direction, snake(), setSnake)
  }
}))

const directionKeys = {
  w: "up",
  a: "left",
  s: "down",
  d: "right"
}

createEffect(on(event, ev => {
  const direction = directionKeys[ev.key];
  if (direction) {
    moveSnake(grid(), setGrid, direction, snake(), setSnake)
  }
}))

It is documented in on.

nikivi•2y ago

  createEffect(
    on(event, (ev) => {
      const direction = directionKeys[ev.key]
      if (direction) {
        moveSnake(grid(), setGrid, direction, snake(), setSnake)
      }
    })
  )

  createEffect(
    on(event, (ev) => {
      const direction = directionKeys[ev.key]
      if (direction) {
        moveSnake(grid(), setGrid, direction, snake(), setSnake)
      }
    })
  )

breaks sadly

nikivi•2y ago

nikivi•2y ago

I still need to wrap ev to check it exists

  createEffect(
    on(event, (ev) => {
      if (ev) {
        const direction = directionKeys[ev.key]
        if (direction) {
          moveSnake(grid(), setGrid, direction, snake(), setSnake)
        }
      }
    })
  )

  createEffect(
    on(event, (ev) => {
      if (ev) {
        const direction = directionKeys[ev.key]
        if (direction) {
          moveSnake(grid(), setGrid, direction, snake(), setSnake)
        }
      }
    })
  )

so this works kind of ugly but I guess needed

Alex Lohr•2y ago

Or you filter event right where you get it.

nikivi•2y ago

yea was going to say but didn't want to bother you more your solution didn't work if (ev) at top works or rather nvm

Alex Lohr•2y ago

Or use createMemo to create a derived event:

const keyEvent = createMemo(last => event().key ? event() : last)

const keyEvent = createMemo(last => event().key ? event() : last)

I'm not bothered.

nikivi•2y ago

yea its ok thank you ❤️

deluksic•2y ago

I did not follow the discussion super closely, but If you want to prevent effects from running on certain signals, use untrack.

Alex Lohr•2y ago

Or on, which tracks only the reactive arguments and ignores the whole rest. Since he uses grid and snake, but only needs to track event, on was simpler.

Gaming

Programming

how can I use createEffect so it doesn't rerun when certain signals change