General Question: Usage of '!'

[srimathiprabhu]

Hi,

I'm new to react js and experimenting on react table. I would like to understand the usage of '!' in the following code snippet.

https://github.com/TanStack/table/blob/main/examples/react/expanding/src/makeData.ts#L32

const newPerson = (): Person => {
  return {
    firstName: faker.name.firstName(),
    lastName: faker.name.lastName(),
    age: faker.datatype.number(40),
    visits: faker.datatype.number(1000),
    progress: faker.datatype.number(100),
    status: faker.helpers.shuffle<Person['status']>([
      'relationship',
      'complicated',
      'single',
    ])[0]!,  <--------- **HERE**
  }
}

export function makeData(...lens: number[]) {
  const makeDataLevel = (depth = 0): Person[] => {
    const len = lens[depth]! <------------ **HERE**
    return range(len).map((d): Person => {
      return {
        ...newPerson(),
        subRows: lens[depth + 1] ? makeDataLevel(depth + 1) : undefined,
      }
    })
  }

[writes-of-spring]

It's a typescript annotation to assert the value is not null or undefined

https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#non-null-assertion-operator-postfix-