What is the best way to add a value to an array in state

Question

I have an array in state, let's say this.state.arr. I want to add something to this state property, and then change some more properties.

Option 1

onChange(event){     this.state.arr.push('newvalue');     ...     this.setState({some:'val',arr:this.state.arr}) } 

Option 2

onChange(event){     var newArr = this.state.arr;     ...     newArr.push('newvalue');     ...     this.setState({some:'val',arr:newArr}) } 

So.. I know this.state is supposed to be treated immutable. But is it ok to use it like in option 1 where I still set the state from it, or do I need to go with something like option 2, and thus always first making a copy in memory

Answer 1

For now, this is the best way.

this.setState(previousState => ({     myArray: [...previousState.myArray, 'new value'] }));