How to change value in array with index in react native

Question

I have an array in my state:

state = {
  some_array: [1,1,1,3,6,3,6,23], // sorry for the syntax it's changed
 }

Now I want to change value in that array that has index let's say 4, and in this case that would be number 6, or if I want to change index 1, that would be second number or array.
I know this is probabbly very simple but I'm just very confused.

If you need more info please comment.

Thanks!

@brk [react-docs](https://reactjs.org/docs/react-component.html#state) says Never mutate this.state directly, as calling setState() afterwards may replace the mutation you made. Treat this.state as if it were immutable. — Taxellool, Aug 29 '18 at 18:05

score 10 · Accepted Answer · answered Aug 29 '18 at 14:25

10

I think that you can to use next code:

const some_array = [...this.state.some_array]
some_array[indexHere] = yourValue
this.setState({some_array:some_array})

This example --- true way for FP in react.

answered Aug 29 '18 at 14:25

Petrashka Siarhei

733
10
12

This is also correct way – crodev Aug 29 '18 at 14:29
It says ```TypeError: Attempted to assign to readonly property.``` – cmcodes May 18 '20 at 18:07
@cmcodes , could you add your code? – Petrashka Siarhei May 20 '20 at 08:31
some_array is assign to const – Ahsan Ullah Jul 23 '20 at 21:28

How to change value in array with index in react native

1 Answers1