How to Update a Nested Object in State Using `setState`?

Update state.item[1] in state using setState

In this situation, you're attempting to update an object within an object in your state using setState. To correctly update the state, you need to make a copy of the entire state object, modify the copy, and then set the state to the updated copy.

Here's how you can update state.item[1] using setState:

<code class="javascript">// 1. Make a shallow copy of the items
let items = [...this.state.items];

// 2. Make a shallow copy of the item you want to mutate
let item = {...items[1]};

// 3. Replace the property you're interested in
item.name = 'newName';

// 4. Put it back into our array. N.B. we *are* mutating the array here, 
//    but that's why we made a copy first
items[1] = item;

// 5. Set the state to our new copy
this.setState({items});</code>

You can combine steps 2 and 3 if you want:

<code class="javascript">let item = {
    ...items[1],
    name: 'newName'
}</code>

Or you can do the whole thing in one line:

<code class="javascript">this.setState(({items}) => ({
    items: [
        ...items.slice(0,1),
        {
            ...items[1],
            name: 'newName',
        },
        ...items.slice(2)
    ]
}));</code>

Note: In these examples, we assumed items was an array. If items was an object, you would make similar updates to the object properties.

Remember, when using setState, you should always make a copy of the previous state before modifying it to ensure that you don't accidentally mutate the original state object.

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