Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
717 views
in Technique[技术] by (71.8m points)

reactjs - Passing array to useEffect dependency list

There's some data coming from long polling every 5 seconds and I would like my component to dispatch an action every time one item of an array (or the array length itself) changes. How do I prevent useEffect from getting into infinity loop when passing an array as dependency to useEffect but still manage to dispatch some action if any value changes?

useEffect(() => {
  console.log(outcomes)
}, [outcomes])

where outcomes is an array of IDs, like [123, 234, 3212]. The items in array might be replaced or deleted, so the total length of the array might - but don't have to - stay the same, so passing outcomes.length as dependency is not the case.

outcomes comes from reselect's custom selector:

const getOutcomes = createSelector(
  someData,
  data => data.map(({ outcomeId }) => outcomeId)
)
See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

You can pass JSON.stringify(outcomes) as the dependency list:

Read more here

useEffect(() => {
  console.log(outcomes)
}, [JSON.stringify(outcomes)])

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...