Typescript 中的函数重载

Function Overloading 可以让同一个函数接受不同个数和类型的参数。如：

interface Coordinate {
  x: number;
  y: number;
}

function parseCoordinate(obj: Coordinate): Coordinate;
function parseCoordinate(x: number, y: number): Coordinate;
function parseCoordinate(arg1: unknown, arg2?: unknown): Coordinate {
  let coord: Coordinate = {
    x: 0,
    y: 0,
  };

  if (typeof arg1 === "object") {
    coord = {
      ...(arg1 as Coordinate),
    };
  } else {
    coord = {
      x: arg1 as number,
      y: arg2 as number,
    };
  }

  return coord;
}

console.log(parseCoordinate(10, 20));
console.log(parseCoordinate({ x: 52, y: 35 }));

TypeScript 可以自动检测到这个函数有3种重载参数，你可以任选一种。