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
For now, this is the best way.
this.setState(previousState => ({
myArray: [...previousState.myArray, 'new value']
}));