How can an array of objects containing different types be mapped using a discriminated union in TypeScript?

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To map an array of objects containing different types using a discriminated union in TypeScript, you can follow these steps:

1. Define a discriminated union type that includes all the possible types of objects in the array. For example:

type MyObject = {
  type: 'type1',
  foo: string,
} | {
  type: 'type2',
  bar: number,
} | {
  type: 'type3',
  baz: boolean,
};

1. Declare an array of objects of type MyObject:

const myObjects: MyObject[] = [
  {type: 'type1', foo: 'hello'},
  {type: 'type2', bar: 42},
  {type: 'type1', foo: 'world'},
  {type: 'type3', baz: true},
];

1. Use the switch statement to map each object in the array based on its type property:

const mappedObjects = myObjects.map(obj => {
  switch (obj.type) {
    case 'type1':
      return obj.foo.toUpperCase();
    case 'type2':
      return obj.bar.toString();
    case 'type3':
      return obj.baz ? 'yes' : 'no';
  }
});

In this example, mappedObjects is an array of strings that corresponds to the original array of objects. Each object is mapped to a string based on its type. Note that the switch statement can include any number of cases depending on how many types there are in the discriminated union.