Definition of interface IDBDatabase, property objectStoreNames is wrong

[lll000111]

The property objectStoreNames of IndexedDB databases is a DOMStringList, not a string array as is set in Flow's type file https://github.com/facebook/flow/blob/v0.41.0/lib/indexeddb.js#L40

I don't know why the MDN page says "obsolete, don't use" about that type - there is no way around it, that is the type of that property. I got bit by Google Chrome (latest stable release) because I tried to use array method includes, but I have to use DOMStringList method contains.

[lll000111]

So it seems that DOMStringList is missing altogether.

Also, the definition of interface IDBRequest's property result is wrong, because right now it is set to IDBRequest. While the MDN page says that too it is wrong, Microsoft's documentation is correct and Mozilla's is wrong. The result can be anything depending on the type of request! For example, when I objectStore.get(...) something from the database result is the returned value.

The whole API with its many events on different levels really is messy, and the MDN documentation is really bad in this case. For example, they never explore what's on those event objects, never even use them in their examples, so no wonder they got it wrong.

I use this definition for DOMStringList:

declare interface DOMStringList {
    length: number;
    item: (number) => string | null;
    contains: (string) => boolean;
}

I use string as type, as far as I can see that is the same as DOMString (but the collection is no array).

Links:

• DOMStringList API overview by Microsoft (for all browsers).
• DOMStringList API overview by Mozilla

FYI, TypeScript had the same issue: microsoft/TypeScript#12069

[lll000111]

The workaround referenced in the link to the private repo is to add this definition to my own .flowDecls/indexeddb.js:

declare interface DOMStringList {
     length: number;
     item: (number) => string | null;
     contains: (string) => boolean;
 }

and further down replace string[]:

    objectStoreNames: DOMStringList;

I didn't make this into a pull request because I'm not sure if this is an "interface" (what I use) or a "class" definition? That definition should then go into lib/dom.js. Interface seems right, but I also don't know where I should place it in that huge file.

This is how TypeScript defines it:

• DOMStringList: https://github.com/Microsoft/TypeScript/blob/master/src/lib/dom.generated.d.ts#L2484
• objectStoreNames: https://github.com/Microsoft/TypeScript/blob/master/src/lib/dom.generated.d.ts#L7005