[Solved] TypeScript: Why Object.fromEntries does not accept array of tuple? [duplicate]

Question

You likely want to use .map here instead of .forEach:

const [itemsWithSelection, setItemsWithSelection] = useState<{ [formFieldId: string]: number }>(itemsWithSelection2)
if (!itemsWithSelection2) {
  let aa = Object.keys(invoiceItems).map((key) =>
    [key, 1]
  )
  setItemsWithSelection(Object.fromEntries(aa))
}

The first produces a new array based on the contents of the callback (or what is often called “closure” in Swift); while the second is used primarily for side effects, and always returns undefined (a value similar to Swift’s Void).

Accepted Answer

You likely want to use .map here instead of .forEach:

const [itemsWithSelection, setItemsWithSelection] = useState<{ [formFieldId: string]: number }>(itemsWithSelection2)
if (!itemsWithSelection2) {
  let aa = Object.keys(invoiceItems).map((key) =>
    [key, 1]
  )
  setItemsWithSelection(Object.fromEntries(aa))
}

The first produces a new array based on the contents of the callback (or what is often called “closure” in Swift); while the second is used primarily for side effects, and always returns undefined (a value similar to Swift’s Void).