useEffect infinite loop when updating state and including dependency array-CodePudding

I always find this a bit weird with React that it is said to be an anti-pattern to not add all dependencies to the useEffect hook and warnings are shown in the console.

Take this example. I am using swr and useSWRInfinite - see example here and docs here.

My code looks checks that a element is inView and if so it fetches the next page of data.

This all works fine

useEffect(() => {
    if (inView) {
      setSize(size   1)
    }
}, [inView, setSize])

but if I add size to the dependency array an infinite loop occurs as I am updating the size within useEffect

useEffect(() => {
  if (inView) {
    setSize(size   1)
  }
}, [inView, setSize, size]) <------ everything breaks

Can anyone advise on the correct way of handling this. After reading through many SO answers and blog posts nothing is any clearer.

CodePudding user response：

You have added size in the dependency array. So, the useEffect will run whenever size changes. Now, in your useEffect, you are incrementing size using the setSize setter. This will again cause size to change and again run the useEffect.

If you want to refer to the previous size, you can use the callback version of the setSize.

setSize((previousSize) => previousSize   1)

This way, your linter won't complain.

CodePudding user response：

You aren't supposed to use the size state inside the setSize. You can change it to setSize(size => size 1) And then remove the size from the dependency array. Can read more here: enter link description here