In this scenario, I am facing a specific dilemma.
type fnArgs = [string, number];
function test(a: string, b: number): void {}
const x: fnArgs = ['a', 2];
test(...x);
What I find interesting is that the values being passed to the test function are coming from an array x. This can be demonstrated in this demo.
Now, my question is whether I can use type fnArgs for the function signature as well. It seems redundant to define string, number twice.
Utilize destructuring in a single line for your tuple:
function test(...[a, b]: fnArgs): void {}
An alternative approach is as follows:
function test(...args: fnArgs): void {}
Here's an example:
function test(a: fnArgs[0], b: fnArgs[1]): void {}
// −−−−−−−−−−−−−−^^^^^^^^^−−−−−^^^^^^^^^
Check it out on the playground here
While a bit repetitive, changing the types in fnArgs will automatically update the function signature.
Just so you know, the same concept applies when using interfaces. For example, if you have a function that retrieves data by an id:
interface Foo {
id: string;
// ...other fields here
}
function makeFoo(id: Foo["id"]): Foo {
// ...
}
(Note: Using Foo.id won't work, use the bracketed form with quotes.)
If the type of id changes from string to number, the function's signature will reflect this change automatically.
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