Is it possible to specify the data types of tuples in a way that allows for type inference as illustrated in the comments within the code snippet below?
declare const tuples: [number, null] | [null, number];
const [a, b] = tuples;
const fun = () => {
if (a === null) {
const c = b; // Can we define the type of 'tuples' so that 'c' is inferred as 'number'???
return;
}
const d = b; // How can we specify the type of 'tuples' so that 'd' infers as 'null'???
}
It's important to avoid destructuring the array until you have identified its type.
Destructuring before determining the specific array type can lead to a disconnection between elements and their corresponding types. For instance, with the initial type of [number, null] | [null, number], accessing elements without confirming the array type first will result in TypeScript assigning a generic type like number | null. This causes TypeScript to analyze variables independently, which can lead to unexpected behavior.
The solution is to delay destructuring until after verifying the array type:
declare const tuples: [number, null] | [null, number];
const fun = () => {
if (tuple[0] === null) {
const [a, b] = tuples
const c = b; // c has type number
return;
}
const [a, b] = tuples
const d = b; // d has type null
}
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