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This
const { foo: IFoo[] } = bar; and this
const { foo: Array<IFoo> } = bar; will reasonably cause an error.
And this
const { foo: TFoo } = bar; will just destructure TFoo property.
How can types be specified for destructured object properties?
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JavaScript Object Destructuring is the syntax for extracting values from an object property and assigning them to a variable. The destructuring is also possible for JavaScript Arrays. By default, the object key name becomes the variable that holds the respective value.
TypeScript casting a destructured object typeconst {firstname: string, age: number} = user; But this assigns the firstname variable to be string and the age variable to be called number . And when we introduce two of the same type, we are hit with an error since we are redefining a variable.
Destructuring is the act of unpacking elements in an array or object. Destructuring not only allow us to unpack elements, it also gives you the power to manipulate and switch elements you unpacked depending on the type of operation you want to perform. Let's see how destructuring works in arrays and objects now.
Destructuring is a JavaScript expression that allows us to extract data from arrays, objects, and maps and set them into new, distinct variables. Destructuring allows us to extract multiple properties, or items, from an array at a time.
It turns out it's possible to specify the type after : for the whole destructuring pattern:
const {foo}: {foo: IFoo[]} = bar; Which in reality is not any better than plain old
const foo: IFoo[] = bar.foo; If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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