no-experimental-features

Warns about elements and attributes marked as experimental in the HTML specification data bundled with markuplint.

info

Split from the former no-unsupported-features rule's checkExperimental option (#3989). Enabling this rule is equivalent to the old checkExperimental: true. See the no-unsupported-browser-features rule for the browserslist-based support check, or the no-nonstandard-features rule for non-standard features.

Not included in any preset: checkExperimental defaulted to false, so this check never ran unless a config asked for it, and enabling the rule stays that same explicit opt-in. Its two siblings are both in markuplint:compat.

Note: Whether an element or attribute is experimental depends on the HTML specification data bundled with markuplint. If a feature is no longer marked as experimental, this rule will not report it.

Default Severity

warning

Options

Option	Type	Default	Description
ignoreFeatures	string[]	[]	Features to ignore.

ignoreFeatures Format

Uses exact string matching (no glob or wildcard patterns).

• "dialog" — Ignores the <dialog> element (exact match on element name).
• "input[list]" — Ignores the list attribute on <input> elements.

Examples

❌ Examples of incorrect code for this rule

<iframe credentialless></iframe>

✅ Examples of correct code for this rule

<iframe></iframe>

Interface

{
  "no-experimental-features": boolean
}

Options

{
  "no-experimental-features": {
    "options": {
      "ignoreFeatures"?: string[]
    }
  }
}

Property	Type	Default Value	Description
ignoreFeatures	string[]	undefined	Features to ignore. Element name ("dialog") or attribute pattern ("input[list]").

Default Severity

warning