React-native: development-level warning are ON, performance optimizations are OFF'

[hahaGitHub]

i pod install react in my own project.and i use RCTRootView to create my UIView.then some information display,as below:
[info][tid:com.facebook.React.JavaScript] 'Running application "TestUI" with appParams: {"rootTag":21,"initialProps":{}}. DEV === true, development-level warning are ON, performance optimizations are OFF'
could you tell me what is the meaning of that?thanks.

[ide]

It's telling you that you're in development mode which means: there are warnings, and performance will be slower. When you load the JS bundle with ?dev=false, you won't get warnings and your JS performance will be faster.

[hahaGitHub]

@ide thanks!1.could you tell me how to set dev=false?2.now,when i shake my iPhone,the js is reloaded,and remind me loading a url like:http://localhost/index.ios.boudle.

[ide]

The issues in this GitHub repository are for bug reports and feature requests only. We don't have the time or people to answer everyone's questions, so please ask your question on Stack Overflow and tag it with "react-native".

[hahaGitHub]

OK thanks

[ghost]

hahaGitHub, did you ever get this working? I am stuck with the same error.

[roysG]

How set development to false?

[gino8080]

how to build for device with DEV = off ?

[engmyahya]

I tried this :
npm start

Then i toggled the mode ,,, i pressed d

Then i wait seconds, and pressed ctrl + c

Then I tried exp start

and got this :

Then the app became run faster.