Why the split declarations in lib.d.ts?

[mindplay-dk]

Why are the declarations in lib.d.ts split into two?

interface Selection {
    anchorNode: Node;
    anchorOffset: number;
    focusNode: Node;
    focusOffset: number;
    isCollapsed: boolean;
    rangeCount: number;
    type: string;
    addRange(range: Range): void;
    collapse(parentNode: Node, offset: number): void;
    collapseToEnd(): void;
    collapseToStart(): void;
    containsNode(node: Node, partlyContained: boolean): boolean;
    deleteFromDocument(): void;
    empty(): void;
    extend(newNode: Node, offset: number): void;
    getRangeAt(index: number): Range;
    removeAllRanges(): void;
    removeRange(range: Range): void;
    selectAllChildren(parentNode: Node): void;
    setBaseAndExtent(baseNode: Node, baseOffset: number, extentNode: Node, extentOffset: number): void;
    toString(): string;
}

declare var Selection: {
    prototype: Selection;
    new(): Selection;
}

Why isn't this declared as a class?

declare class Selection {
    constructor();

    anchorNode: Node;
    anchorOffset: number;
    focusNode: Node;
    focusOffset: number;
    isCollapsed: boolean;
    rangeCount: number;
    type: string;
    addRange(range: Range): void;
    collapse(parentNode: Node, offset: number): void;
    collapseToEnd(): void;
    collapseToStart(): void;
    containsNode(node: Node, partlyContained: boolean): boolean;
    deleteFromDocument(): void;
    empty(): void;
    extend(newNode: Node, offset: number): void;
    getRangeAt(index: number): Range;
    removeAllRanges(): void;
    removeRange(range: Range): void;
    selectAllChildren(parentNode: Node): void;
    setBaseAndExtent(baseNode: Node, baseOffset: number, extentNode: Node, extentOffset: number): void;
    toString(): string;
}

These split declarations are seen as two declarations by VS Code, which doesn't work very well, e.g. doesn't show you the interface members in the pop-up:

Can't you merge these?

[plantain-00]

This link may help: https://github.com/Microsoft/TypeScript-Handbook/blob/master/pages/Writing%20Declaration%20Files.md#class-decomposition

[mhegazy]

Why are the declarations in lib.d.ts split into two?

The reason is rather historic. back in 0.8.* time classes and interfaces did not merge, and we wanted these classes to be extensible.

The other part that makes blocks this conversion across the board is call signatures. there is no way now to define a call signature on a class. this is tracked by #183.

As @plantain-00 noted; the result of the split should not be of any much consequence. moving to classes, would allow extending the static side, which is not allowed now. not sure that this is a common scenario however.

Can't you merge these?

They can. I do agree it makes the declaration file cleaner and easier to read. this request is tracked by #574