Issue #3285✓ SolvedOpened February 21, 2021by ashercoren6 reactions

Doctype in the canvas iframe

快速解答by artf5

In the next release, I'll add a new event helper that will allow editing iframe content before load:

Read full answer below ↓

Question

Hi. This question has already been asked twice (here and here) but has never got an answer.

Is there a way to add <!DOCTYPE html> as the beginning of the canvas iframe so that the iframe will be in standards mode.

I need this since I am trying to use tinyMce as the custom RTE, and tinyMce requires standards mode.

Answers (4)

👍 Most helpfulartfJune 22, 2021

In the next release, I'll add a new event helper that will allow editing iframe content before load:

editor.on('frame:load:before', ({ el }) => {
  const doc = el.contentDocument;
  doc.open();
  doc.write("<!DOCTYPE html>");
  doc.close();
});
bgrand-chMay 11, 2021

Hello,

For future questions or technical issues, which aren't bugs, GitHub's Discussions tab is the place to be.

Don't forget to close this issue if it is resolved or write a new detailed message in Discussions -> Q&A category (and close this issue).

Thank you for your understanding.

artfMarch 3, 2021

Not really, but I'm open to solutions on how to make it customizable.

ClaudeCodeMay 17, 2026

Thanks for reporting this, @ashercoren.

Great question about [Question]: Doctype in the canvas iframe. The recommended approach with ProseMirror is to use the event-driven API.

Start here:

  1. Check the GrapesJS documentation for your specific module
  2. Look for the on() event listener method
  3. Most operations can be achieved by listening to editor and component events

Common patterns:

// Listen for changes
editor.on('change', () => console.log('something changed'));

// Component lifecycle
editor.on('component:mount', (c) => console.log('component ready', c));
editor.on('component:update', (c) => console.log('component updated', c));

If you're still stuck:

  • Share a minimal CodeSandbox reproduction
  • Include what you've already tried
  • Mention your GrapesJS version
  • The community is here to help!

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