1. Form validation

    Method of setting required fields and field types without requiring JavaScript. This includes preventing forms from being submitted when appropriate, the `checkValidity()` method as well as support for the `:invalid`, `:valid`, and `:required` CSS pseudo-classes.

  2. elementinternals api: ariainvalid

  3. element api: ariainvalid

  4. htmlgeolocationelement api: invalidreason

  5. htmlinputelement api: `invalid` event

  6. htmlinstallelement api: invalidreason

  7. webgl2renderingcontext api: invalidateframebuffer

  8. webgl2renderingcontext api: invalidatesubframebuffer

  9. xpathresult api: invaliditeratorstate

  10. css at-rule: `@font-face`: src: drop invalid item (not src string)

  11. css selector: `:invalid`

  12. css selector: `:invalid`: applies to `<form>` elements

  13. css selector: `:user-invalid`

  14. html element: input: `type="date"`: disables invalid values in picker ui