add item to array(Hooks) react js

Question

I watch course about react js and And in it Adds a new item to the array(hook) as follows:

useState([new item , old Array]);

But I repeat this, the array turns into an object

Whatever I searched for, I saw the following result:

useState([ old array ,new item ]);

But the method worked well in the course

Sean · Accepted Answer · 2021-04-05 07:32:39Z

2

To add items to an array using React hooks you need to use the spread operator to get the old array and then add the new item.

setState([...oldArray, newItem])

answered Apr 5, 2021 at 7:32

Sean

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1 Comment

@Morteza.s17 make sure you use the setState function and not useState when updating it which is what you have in your question

Aleksandr Bagrintsev · Accepted Answer · 2021-04-05 07:37:06Z

2

You should use the spread operator: setState(prev => [...prev, newItem]);

answered Apr 5, 2021 at 7:37

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Fardeen Panjwani · Accepted Answer · 2021-04-05 07:38:14Z

1

A better way of updating an array using react-hooks is to pass in a callback function to the hook, like this:

setState((oldState) => [...oldState, newItem])

This is considered a best practice and is a lot more performant than directly spreading the old state.

answered Apr 5, 2021 at 7:38

Fardeen Panjwani

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