How to fix this error in TypeScript?

Question

typescript

This overload signature is not compatible with its implementation signature.

The code:

function printInc(a: number): void;
function printInc(a: string): void {
    switch (typeof a) {
        case 'string':
            console.log(a + ' plus one');
            break;
        case 'number':
            console.log(a + 1);
            break;
    }
}

URL:
https://www.typescriptlang.org/play?ssl=1&ssc=22&p...

Answer 1

function printInc(a: string | number): void {
  switch (typeof a) {
    case 'string':
      console.log(a + ' plus one');
      break;
    case 'number':
      console.log(a + 1);
      break;
  }
}