What is exclamation mark here?...old[rowIndex]!

[madrimovganijon]

Following editable data example for react. Piece of the code for updateData looks like the following. What is ! here? Typo?

setData(old =>
          old.map((row, index) => {
            if (index === rowIndex) {
              return {
                ...old[rowIndex]!,
                [columnId]: value,
              }
            }
            return row
          })

[KevinVandy]

Look it up in the Typescript docs

[madrimovganijon]

Got it thanks. Typescript is not as simple as I thought after all.