ReactJS setState multidimensional array variable keys in sub array

Question

I have an array of components which each have component details and I'm trying to update a detail for a component.

I know I can do this

this.setState({
    component: {
       ...this.state.component,
       [var]: value
    }
});

but I need to be able to do this

this.setState({
    component[key]: {
       ...this.state.component[key],
       [key2]: value
    }
});

which fails. How can I modify a sub array without modifying state and replacing the whole thing?

Answer 1

You would need to update the nested data within component state as well

this.setState({
    component: {
       ...this.state.component,
       [key]: {
          ...this.state.component[key],
          [key2]: value
       }
    }
});

However when you are updating state based in previous state, it preferable to use callback method to update state

this.setState(prevState: ({
    component: {
       ...prevState.component,
       [key]: {
          ...prevState.component[key],
          [key2]: value
       }
    }
}));