HTMLTableElement caption/tHead/tFoot setters exception inconsistencies

[TRowbotham]

• HTMLTableElement.caption

  Does not mention anything about throwing an exception when the new value is neither null nor HTMLTableCaptionElement, but setting to a value that is neither of these causes a TypeError to be thrown.

• HTMLTableElement.tHead

  The setter steps say that setting to a value that is neither null nor HTMLTableSectionElement should throw a HierarchyRequestError, but browsers seem to throw a TypeError instead.

• HTMLTableElement.tFoot

  Same as HTMLTableElement.tHead.

Tested in Firefox and Edge Chromium.

Example:

const t = document.createElement('table');
const a = document.createElement('a');

t.caption = a;
t.tHead = a;
t.tFoot = a;

[domenic]

These TypeErrors are generated by the Web IDL for these properties: as defined in https://html.spec.whatwg.org/multipage/tables.html#htmltableelement plus https://heycam.github.io/webidl/#dfn-attribute-setter step 4.6.

This is the general pattern used by all web platform API specification setters.

I'll close this, since the specification covers this, but feel free to ask any further questions about this behavior in case there's something I missed.

[TRowbotham]

Thanks for the reply. I had thought that perhaps the HierarchyRequestErrors were redundant, since I figured this was getting caught at the IDL layer, but after trying a little harder, I found that browsers do actually throw a HierarchyRequestError under at least one condition; when tHead/tFoot are given an element implementing the correct interface (i.e. an HTMLTableSectionElement), but having the wrong local name. A minor detail thats not worth nit picking over.

const t = document.createElement('table');

t.tHead = document.createElement('a'); // TypeError
t.tHead = document.createElement('tbody'); // HierarchyRequestError