Typescript函数与对象重载

Question

I have a function that accepts an object as the only parameter. For example:

interface MyMap<T> {
  [id: string]: T;
}

type Options = {
  asObject: boolean,
  other?: Function
};

  function get(options: Options): any[];
  function get(options: Options): MyMap<any>;
  function get(options: Options): any[] | MyMap<any>;
  function get(options: Options = {asObject: false, other: () => {}}): any[] | MyMap<any> {
    if (options.asObject) return {} as MyMap<any>;

    return [];
}


const result = get({asObject: true});

When the asObject value is true, I want to infer the type to MyMap. I know how to do it with simple boolean value, but how can I accomplish this with an object?

Answer 1

function get(options: {asObject: true}): MyMap<any>;
function get(options: {asObjectb false}): any[];
function get(): any[];
function get(options: Options = {asObject: false, other: () => {}}): any[] | MyMap<any> {
   //  ... 
}

Should be all that you need. This will overload the function for the literal types true and false of the property asObject .

Note that when overloads are declared, the implementation itself does not contribute a signature to the overload set.