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無料 contenteditable=plaintext-onlyジェネレーター

リッチテキストフォーマットなしのプレーンテキスト入力のためのcontenteditable=plaintext-onlyアクセシブルHTMLマークアップを生成します。

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contenteditable=plaintext-onlyジェネレーターとは

The contenteditable=plaintext-only attribute creates an HTML element that users can edit, but unlike contenteditable=true which accepts rich text formatting (bold, italic, colors, fonts), plaintext-only strips all formatting on paste. When a user copies formatted text from Word, Google Docs, or a web page and pastes it into a plaintext-only editor, the pasted content is plain text only -- no HTML tags, no inline styles, no font formatting. This behavior is built into the browser and requires zero JavaScript.

クイックアンサー

Use contenteditable=plaintext-only to create editable regions that accept plain text only -- pasting formatted content strips all HTML tags and inline styles automatically. No JavaScript needed. Supported in Chrome 120+, Edge 120+, Safari 17.4+, and Firefox 136+. Degrades gracefully to rich text editing in older browsers. The generated HTML includes placeholder CSS, focus styles, ARIA attributes, and optional fallback detection.

制限事項

Not supported in Firefox before version 136. The attribute degrades to contenteditable=true gracefully, so users on older Firefox versions see a rich text editor instead of a plain-text editor. Add a JavaScript paste interceptor as a safety net for these users.
plaintext-only is an all-or-nothing approach -- it does not support allowing some formatting (like line breaks) while blocking others (like bold or fonts). For selective filtering, you need a custom solution with the beforeinput event.
Browser implementations may differ in edge cases -- for example, how trailing whitespace, multiple spaces, or unusual Unicode characters are handled on paste. Test with the types of content your users are most likely to paste.

使い方

Choose the editor mode: plaintext-only (strips all formatting on paste) or regular contenteditable (preserves rich text). Generate HTML for either mode or both with a side-by-side comparison.
Configure placeholder text that appears when the editor is empty, and customize the placeholder CSS color and styling to match your design.
Set focus styles: outline, border color, or box-shadow that activates when the editor receives focus. Include ARIA labels for screen reader accessibility.
Copy the generated HTML markup. The tool provides a complete, self-contained snippet with associated CSS that handles fallback detection for browsers that do not yet support plaintext-only.

主な用途

Comment fields and discussion forums where users should not be able to paste formatted text that breaks the page layout or introduces hidden HTML.
Code snippet inputs or configuration editors where raw text is expected and rich formatting is unwanted noise.
Internal note-taking tools or CMS plain-text descriptions where formatting adds complexity without benefit.

用途

使用例

例

Blog comment plaintext field

A blog wants to prevent commenters from pasting formatted text with hidden HTML tags that could break the layout or introduce XSS vectors. Use contenteditable=plaintext-only for the comment input. When a user copies a formatted paragraph from Word and pastes it, the browser strips all bold, italic, font, and color tags automatically -- the result is clean plain text.

例

Configuration editor comparison

A developer tool needs two input modes: a WYSIWYG editor for rich descriptions (contenteditable=true) and a plain-text field for configuration values (contenteditable=plaintext-only). Use the generated HTML to show both modes side by side so users understand the difference immediately.

よくあるミス

Using contenteditable=true for plain-text fields and writing JavaScript paste interceptors to strip formatting -- the browser does it for you with plaintext-only, saving code, maintenance, and edge-case bugs.
Forgetting to add ARIA attributes and accessible labels to contenteditable regions -- screen readers treat editable elements as form controls and require proper labeling via aria-label or aria-labelledby.
Not testing the fallback behavior in older browsers -- Firefox added plaintext-only in version 136. Without a fallback, users on older versions get a regular rich text editor instead.

検証

Open the generated HTML in Chrome or Safari. Type some text, then copy a formatted paragraph from a web page or Word document and paste it into the editor. Verify that all formatting (bold, italic, colors, fonts, links) is stripped and only plain text remains.
Test the same paste operation in Firefox 135 or earlier to confirm the fallback behavior -- the editor should work as contenteditable=true (preserving formatting) since plaintext-only is not supported. If you added the optional JavaScript fallback, verify it intercepts paste events in older browsers.

FAQ

contenteditable=plaintext-onlyジェネレーターのFAQ

How does contenteditable plaintext-only differ from contenteditable true?

contenteditable=true allows users to edit HTML content and paste formatted text, preserving bold, italic, lists, links, and inline styles. contenteditable=plaintext-only strips all formatting on paste, including HTML tags, inline styles, and rich text from Word or web pages. The underlying editing behavior is identical -- only paste handling differs. plaintext-only behaves as if a JavaScript paste interceptor ran document.execCommand(insertText) every time, but with no code required.

Which browsers support contenteditable=plaintext-only?

As of 2026, plaintext-only is Baseline 2025 supported in Chrome 120+, Edge 120+, Safari 17.4+, and Firefox 136+. This covers approximately 85% of global browser usage. For older browsers, the attribute degrades gracefully to contenteditable=true (rich text). The generated HTML includes fallback detection so you can add a JavaScript paste interceptor as a safety net for older browsers.

Can I allow some formatting but block others with plaintext-only?

No -- plaintext-only is an all-or-nothing behavior. If you need selective filtering (for example, allowing line breaks but blocking font tags), you must write a custom paste handler with the beforeinput event or use a library like Quill or TipTap that provides configurable paste sanitization. plaintext-only is intended for cases where you want zero formatting, not custom filtering.

Does contenteditable plaintext-only prevent XSS?

It reduces one XSS vector: pasted HTML that contains script tags, event handlers, or other malicious markup is stripped to plain text, so those tags never enter the DOM. However, contenteditable regions are still editable HTML elements and can be targeted by other attack vectors. Always validate and sanitize content on the server side before storing or displaying it, regardless of the contenteditable mode.