React project render twice?

[zpc7]

🐛 bug report

Description of the problem

When I do some optimization about react project, I found the react function 'render' execution twice, no matter when the Initialization process and the react state change. It make me very confusion +_+

How has this issue affected you? What are you trying to accomplish?

I cannot observed the project correct behavior.. The function should be execution only once.

Link to sandbox: link

Your Environment

Software	Name/Version
Сodesandbox	PROD-1582498771-d91b0f8b1
Browser	Chrome 80.0.3987.122
Operating System	macOS 10.15.3 (19D76)

[jyash97]

Hey @zpc7

This is because you are wrapping the component with React.StrictMode and it re-renders intentionally. Check the thread here: facebook/react#12856.

Also removing StrictMode renders as expected. Link: https://codesandbox.io/s/react-sandbox-render-twice-hbixn

[zpc7]

@jyash97 Oh It's Cool !
Not careful enough for myself. Thank you very much.
I will close the issue also.