customElement decorator should use type string for tagName

[sorvell]

This is currently keyof HTMLElementTagNameMap but this doesn't work nicely in TypeScript right now and the result is you have to cast to any. Instead we should just use string for now.

[jhpratt]

Seconding this. I just ran into this issue while testing out lit element on an existing component.

[nrdobie]

It looks like the issues is that TypeScript is converting keyof HTMLElementTagNameMap to "object" | "a" | "abbr" | "acronym" | "address" | "applet" | "area" | "article" | "aside" | "audio" | "b" | "base" | "basefont" | "bdo" | "big" | "blockquote" | "body" | "br" | "button" | "canvas" | "caption" | "center" | "cite" | "code" | "col" | "colgroup" | "data" | "datalist" | "dd" | "del" | "dfn" | "dir" | "div" | "dl" | "dt" | "em" | "embed" | "fieldset" | "figcaption" | "figure" | "font" | "footer" | "form" | "frame" | "frameset" | "h1" | "h2" | "h3" | "h4" | "h5" | "h6" | "head" | "header" | "hgroup" | "hr" | "html" | "i" | "iframe" | "img" | "input" | "ins" | "isindex" | "kbd" | "keygen" | "label" | "legend" | "li" | "link" | "listing" | "map" | "mark" | "marquee" | "menu" | "meta" | "meter" | "nav" | "nextid" | "nobr" | "noframes" | "noscript" | "ol" | "optgroup" | "option" | "output" | "p" | "param" | "picture" | "plaintext" | "pre" | "progress" | "q" | "rt" | "ruby" | "s" | "samp" | "script" | "section" | "select" | "slot" | "small" | "source" | "span" | "strike" | "strong" | "style" | "sub" | "sup" | "table" | "tbody" | "td" | "template" | "textarea" | "tfoot" | "th" | "thead" | "time" | "title" | "tr" | "track" | "tt" | "u" | "ul" | "var" | "video" | "wbr" | "xmp" for the declaration file instead of keeping the keyOf. Probably just an incorrect setting in TypeScript.

[jhpratt]

@nrdobie That's because that long list is what keyof HTMLElementTagNameMap is equivalent to. That's not a wrong setting at all; lit-element currently requires you to manually extend the interface. I don't think that should be necessary, and switching to string would suffice (rather than casting to any).

[nrdobie]

@jhpratt what I meant by incorrect setting was TypeScript reducing it down to that list of strings rather then preserving the keyof statement. Based on the current expected behavior of lit-element, preserving the keyof would make the behavior work as expected. Changing to string does also work as well but also changes the behavior.

[legowerewolf]

Just ran into this, would be a nice fix. @nrdobie how would changing to string change the behavior?

[nrdobie]

Functionally it won't but it doesn't require the HTML tag list to be updated for TypeScript. I know I'm splitting hairs and I don't really have a strong opinion. I can union this with string and get the best of both.

…

On Fri, Dec 7, 2018, 3:22 PM Duncan ***@***.***> wrote: Just ran into this, would be a nice fix. @nrdobie <https://github.com/nrdobie> how would changing to string change the behavior? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#291 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAq41T08B9bQBnclEJtUBmCfmAl-RDzoks5u2twzgaJpZM4YPcps> .

[vladnicula]

Can someone explain the reasoning for having keyof HTMLElementTagNameMap there? I don 't fully understand why this wasn't a string in the first place.

[sorvell]

Fixed via #292.