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Start your free trialBegana Choi
Courses Plus Student 13,126 Pointswhy don't we use prevState in tick function for ( now - this.state.previousTime )?
prevState is the better way to verify that state did update correctly. but why we don't use prevState for this part?
tick = () => {
if(this.state.isRunning){
const now = Date.now();
this.setState( prevState => ({
previousTime: now,
elapsedTime: prevState.elapsedTime + ( now - this.state.previousTime ) <<this part
}))
}
}
1 Answer
Mia Filisch
16,117 PointsI was just wondering the same thing! My understanding is that it's always better to use prevState
than this.state
when updating state based on existing state, so I assume this is simply an oversight. I used prevState
in both places and it seems to work fine!