Proper Way to Set State in ReactJS

ReactJS State manipulation should be done by mutating prevState and not directly to avoid undesired results. In the tutorial we are exploring a little bit more on the topic of react state management. Question is, how can you set state correctly in ReactJS. Which is proper way of mutating state in ReactJS? we will create a simple counter and increment its value each time when a button is clicked. And we will mutate the state properly.