feat(index): move isInitialized to aurelia-pal

[niieani]

It makes sense to have isInitialized in aurelia-pal, not in each individual -pal repository, otherwise you can initialize it multiple times with different PALs by mistake, which is probably not the desired behavior. I've added a reset() function just in case somebody wants to purposefully reinitialize PAL with a different version.

Related PRs for all PALs:

• feat(index): move isInitialized to aurelia-pal pal-browser#14
• feat(index): move isInitialized to aurelia-pal pal-worker#4
• feat(index): move isInitialized to aurelia-pal + globalize function pal-nodejs#20

[EisenbergEffect]

Is this correct for history and location? I get that Element isn't an instance of Element but is the type itself but history and location are the instances of history and location.

[niieani]

@EisenbergEffect Yeah, this is correct. typeof in TypeScript doesn't mean "the class of X", but simply "same type as X". So "typeof window.history" is the type of an instance of history.

[niieani]

@MeirionHughes I've checked this. The reason last one came out wrong is you have an error in your example. Last example should be:

let foo = new Foo();
let foo2: typeof foo = foo;

Since you used typeof Foo instead of typeof foo you got the ctor of Foo, not referenced type of the variable foo.

Going back to the actual problem, history is a property of the window object. So typeof window.history is the type of the variable on the Window object, i.e. type of the instance of History.

[MeirionHughes]

... never mind; its fine because the typeof target is an instance, so it grabs the type.

[EisenbergEffect]

Just need some clarification on my question. Otherwise, I can merge this. Let me know.