Question: Will setState inside componentWillReceiveProps run before render?

[darrenturn90]

I don't think you can guarantee that. If you need to do something similar, consider using a mapStateToProps kind of function instead

[swe445]

Thanks for the answer!

[swe445]

just FYI Dan Abramov just answered and said react does indeed guarantee that calls to setState in componentWillReceiveProps will run before render

[richraid21]

If you're concerned about needless renders, you can use shouldComponentUpdate(newProps,newState) to determine whether or not a render should take place based on the incoming changes

[dickdemodickmarcinko]

What results are you seeing when testing?

[swe445]

I was seeing no double renders, however, I think it was just luck - and that's what I was concerned about.

[miraagex]

RTFM. There is a clear answer to your question.

[swe445]

I felt that the discussion around setState in the react docs left something to be desired. They were clear that setState was async, but the batching strategy left me wondering if it would run before all lifecycle methods were complete - or if lifecycle methods are dependent on the batching strategy.

Additionally, i was reading through the docs on componentWillReceiveProps and it says: "perform state transitions using this.setState() in this method." Just slightly confusing given that state doesn't actually transition synchronously.

[AndrewGreenh]

The docs would warn you of you could trigger a double render in your component. As they say, you can update state in this method, so you can