Deconstruct an object that may potentially be undefined in a parameter list using a single line of code

Suppose there is an interface called MyType:

interface MyType {
  options?: { field0: string, field1: string, field2: string };
}

If we are mapping over an array named myArray, which has the type MyType[], we can destructure the options attribute in this way:

myArray.map(({ options }) => {
 const { field0, field1, field2 } = options!;

It's important to note the use of the bang operator (!) as options could potentially be undefined.

I attempted to turn this into a one-liner like so:

myArray.map(({ options: { field0, field1, field2 }}) => {

However, this resulted in errors such as "Property 'field0' does not exist on type 'MyType | undefined'" due to the typing of options.

In situations like this, usually I can include the bang operator to skip the undefined check.

I tried doing it as a one-liner:

myArray.map(({ options: { field0, field1, field2 }!}) => {

and also:

myArray.map(({ options!: { field0, field1, field2 }}) => {

Both attempts were not valid syntax.

Is there a way to destructure an object that may be undefined in a one-liner format within a parameter list?

Answer №1

If you're confident that the array solely comprises objects with options, you can perform a type assertion on the array itself:

(myArray as Required<MyType>[]).map(({ options: { field0, field1, field2 }}) => {

Another approach that allows for using the non-null assertion involves mapping in two stages:

myArray.map(el => el.options!).map({ field0, field1, field2 }) => {

Nevertheless, the recommended safe practice is to take into account the possibility of certain array elements lacking options, and assign those defaults to an empty object:

myArray.map(({ options: { field0, field1, field2 } = {}}) => {

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