如何在 ArrayObject React native 中设置状态数组

Question

I've been sitting around for a while trying to figure out how to do this I've scoured a lot of documentation on StackOverFlow (maybe I missed it)

this.state = {
        data: {
                labels: [],
                datasets: [
                    {
                        data: []
                    }
                ]
            }
        };

i tried with below code how can i setState CONCAT for 2 arrays Labels:[] and data:[]

my code:

  this.setState(a => ({
       data: {
          labels: this.state.data.labels.concat(x.month), <- is this correct?
          datasets: [
                      {
                        data: this.state.data.datasets.map(x=> x.data.concat(x.money/1000))
                     or //data: this.state.data.datasets[0].data.concat(x.money/1000))
                       }
                    ]
              }
           }
        )
     )

JS

data: {

                labels: [],
                datasets: [
                    {
                        data: []
                    }
                ]
       }

how to point to data array?

Answer 1

As you might be aware, the state update in react/react-native are asynchronous. Therefore the code you have written might cause some weird behavior sometimes. For example, simultaneously multiple function call for that state update might lead to the unexpected end state.

Instead, you can update your state as following

this.setState((state, props) => ({
   data: {
      labels: state.data.labels.concat(x.month),
      datasets: state.data.datasets.map(({data}) => ({data: data.concat(x.money/1000)}))
    }
  })
)