I came across this method signature:
export function retry<T>(this: Observable<T>, count: number = -1): Observable<T> {
return higherOrder(count)(this) as Observable<T>;
}
The first parameter is this and it is typed as Observable<T>. I noticed that having this as an argument may seem incorrect, but the compiler accepts this syntax and I have seen this pattern used a few times before. Can someone explain what its purpose is?
According to this stackoverflow post:
Explicitly Specifying the Type of 'this' in TypeScript Functions Continuing on from specifying the type of 'this' in a class or interface, TypeScript now allows functions and methods to declare the type of 'this' they require.
By default, the type of 'this' inside a function is any. With the introduction of TypeScript 2.0, developers can define an explicit this parameter. These this parameters are dummy parameters placed at the beginning of a function's parameter list:
function f(this: void) {
// ensures that `this` is not accessible within this isolated function
}
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