HTML Preview and Validator は何をしますか？
HTML Preview and Validator はブラウザ上でデータを調査するツールで、結果と制限を明確に示します。 検証済みの機能： Sandboxed HTML preview, Duplicate ID detection, Image alt checks, Form-label checks.
Use local preview for fast feedback, Nu for conformance
This page is suited to safe visual inspection and common structural mistakes. It does not claim complete HTML or accessibility validation.
使い方
- Paste an HTML document or fragment.
- Choose Preview for sandboxed rendering or Validate structure for deterministic checks.
- Fix reported document, duplicate-ID, image-alt, or form-label issues and rerun.
実際の入出力例
Find a missing image alternative
入力
<main><img src="photo.jpg"><p>Hello</p></main>出力
Warning: 1 image is missing an alt attribute.The local DOM inspection catches a common accessibility defect without loading a remote validator.
一般的なエラーと対処
| 症状 | 原因 | 対処 |
|---|---|---|
| Scripts do not run in the preview. | The iframe intentionally has a restrictive sandbox. | Use a controlled development environment when script execution is required. |
| No warning appears for a standards issue. | The tool performs focused structural checks, not full conformance validation. | Use the Nu HTML Checker for release-grade standards validation. |
Important behavior of HTML Preview
このツール固有の制限： These deterministic checks are not a substitute for the complete WHATWG conformance rules or the W3C Nu validator.
標準と実装の参考資料
- WHATWG HTML Living Standard (opens in a new tab)Defines HTML parsing and document conformance.
- Nu HTML Checker (opens in a new tab)Provides comprehensive standards-oriented HTML checking.
HTML Preview — FAQ
Does the HTML Preview upload my input?
No. Processing runs in the current browser tab, and the page does not send tool input to a KitLumi processing endpoint.
What input does the HTML Preview accept?
It accepts an HTML document or fragment. The workspace checks the input and reports malformed or unsupported values before it produces a result.
What does the HTML Preview produce?
It produces a sandboxed preview and local diagnostics for document, image, ID, and form-label structure. Copy and download controls appear when the output format supports them.
What limitation should I know?
These deterministic checks are not a substitute for the complete WHATWG conformance rules or the W3C Nu validator.
更新内容
実質的な更新： HTML Preview: Added Sandboxed HTML preview, Duplicate ID detection, Image alt checks, Form-label checks, responsive controls, explicit runtime disclosure, and task-specific examples and limitations.