Currently, I am in the process of creating a type definition file called index.d.ts for a jQuery library that does not have its own type definition.
The functions within this library repeatedly accept parameters with multi-types (string | number | []), so I have defined a custom type called CustomType:
export type CustomType = string | number | [];
declare global {
interface JQuery<TElement = HTMLElement> {
setFoo(foo: CustomType): this;
setBar(bar: CustomType): this;
}
}
When I try to call the setFoo() function on a jQuery object, the type hinting in IntelliJ indicates that a parameter foo: CustomType is expected. This can be confusing for other developers without prior knowledge of what this type represents.
Instead, I would prefer the type hinting to display foo: string | number | [].
In C++, there exists the concept of an inline function, which instructs the compiler to insert the code directly at the calling location rather than jumping to the function's body. Is there a similar feature in TypeScript?
Is there a way to make TypeScript display foo: string | number | [] instead of foo: CustomType through some form of inlining?
Potential Solution
declare global {
interface JQuery<TElement = HTMLElement> {
setFoo(foo: string | number | []): this;
setBar(bar: string | number | []): this;
}
}
An option could be to remove the CustomType and explicitly specify parameter types as their corresponding multi-types. However, this approach becomes cumbersome when dealing with numerous methods that share the same type, lacking reusability while appearing unappealing.
Desired Solution
export type CustomType = string | number | [];
declare global {
interface JQuery<TElement = HTMLElement> {
setFoo(foo: inline CustomType): this; // <-- 'inline' notation
setBar(bar: inline CustomType): this;
}
}
This theoretical solution would mirror the behavior of the previous "Potential Solution," but sadly, it is not supported. What would be the correct approach to achieve this desired outcome?