Anyone know what does this mean :
myCollection: Collection|any = null;
?
I'm trying to figure it out but I am not sure..
Does it mean that myCollection is defined as a type of Collection, (which is an interface), and that its value is null by default? But if so, what does this :
|any
Means ?
| is a union. The type A | B means "either A or B or both".
any is the any "type", which you generally shouldn't be using because it effectively turns off type checking by being assignable both to any other type and from any other type. This also means that any gobbles up any type that it appears with in a union or an intersection.
The type Collection | any therefore means "either a Collection or any type whatsoever". This reduces immediately to just any by the compiler, since that "either A or anything" is just "anything":
myCollection: Collection | any = null;
// (property) Foo.myCollection: any
So Collection | any is at best useful for documentation; as far as the compiler is concerned, Collection | goes away.
And the property is initialized to null.
I'm not sure if this is someone else's code or yours. If it's yours, consider changing to Collection | null if the intent is that the property can be a Collection or null. If it's someone else's, uh, ask them what's up with it I guess?
It means that myCollection can be of type Collection or of type any and it is initialized to null
In Collection|any this type, | indicates Union Type
Meaning of this is, variable mycollection can hold value of type Collection OR type of any.
Because mycollection can be of type any, null is valid value and typescript allows you to assign null to mycollection.
