ts(2339) Property does not exist on type - Destructuring-CodePudding

I wrote a function that returns a helper method based on a record type or the default helper if it's undefined, but ts complains about it. Is it possible to fix it without defining every member of Types? I didn't want to use if / switch

type Types = 'foo' | 'bar' | 'baz';

const fooHelper = () => console.log('fooHelper');

const getHelper = (t: Types) => {
  const defaultHelper = () => console.log(t);

  // Property 'bar' does not exist on type '{ foo: () => void; }'.ts(2339)
  // Property 'baz' does not exist on type '{ foo: () => void; }'.ts(2339)
  const { [t]: helper = defaultHelper } = {
    foo: fooHelper,
  };

  return helper;
};

CodePudding user response：

You'll need set the type of your object as having all the keys as optional :

type SomeTypes = { [P in Types]?: unknown }

Which gives us this :

type Types = 'foo' | 'bar' | 'baz';

type SomeTypes = { [P in Types]?: unknown }

const fooHelper = () => console.log('fooHelper');

const getHelper = (t: Types) => {
    const defaultHelper = () => console.log(t);

    const someTypes: SomeTypes = { foo: fooHelper };
    const { [t]: helper = defaultHelper } = someTypes;

    return helper;
};

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