Add SVGElementTagNameMap

[justinfagnani]

TypeScript Version: 2.2.1

APIs that use ElementTagNameMap or HTMLElementTagNameMap could benefit the same from a SVGElementTagNameMap.

[mhegazy]

HTMLElementTagNameMap is only used for createElement, and as far as i understand createElement does not generate SVGElements, so what APIs did you have in mind?

[falsandtru]

I want this too. When we make some SVGElement builder, need to define its type as

createElement<K extends keyof SVGElementTagNameMap>(tagName: K): SVGElementTagNameMap[K];

to avoid the built-in method that requires specifying namespace URI.

createElementNS(namespaceURI: "http://www.w3.org/2000/svg", qualifiedName: "a"): SVGAElement;

But SVGElementTagNameMap doesn't exist. Can you accept this PR?

[falsandtru]

e.g.

type TypedHTML = {
  //readonly [K in keyof HTMLElementTagNameMap]: ElBuilder<K, HTMLElementTagNameMap[K]>;
  readonly [K in keyof ElementTagNameMap]: ElBuilder<K, ElementTagNameMap[K]>;
};
export const TypedHTML: TypedHTML = new Proxy({} as TypedHTML, {
  get: (obj, tag) =>
    obj[tag]
      ? obj[tag]
      : obj[tag] = builder(NS.HTML, `${tag}`),
});

/*
type TypedSVG = {
  readonly [K in keyof SVGElementTagNameMap]: ElBuilder<K, SVGElementTagNameMap[K]>;
};
export const TypedSVG: TypedSVG = new Proxy({} as TypedSVG, {
  get: (obj, tag) =>
    obj[tag]
      ? obj[tag]
      : obj[tag] = builder(NS.SVG, `${tag}`),
});
*/

  function factory_(): E {
    switch (ns) {
      case NS.HTML:
        return document.createElement(tag) as Element as E;
      case NS.SVG:
        return document.createElementNS("http://www.w3.org/2000/svg", tag) as Element as E;
      default:
        throw new TypeError(`TypedDOM: Namespace must be "${NS.HTML}" or "${NS.SVG}", but got "${ns}".`);
    }
  }

https://github.com/falsandtru/typed-dom/blob/master/src/dom/html.ts

[falsandtru]

I made a PR microsoft/TypeScript-DOM-lib-generator#324

[falsandtru]

@RyanCavanaugh @mhegazy Can you take a look?