Comment Extension

The comment extension provides a mechanism to make comments within markdown text that will not be rendered in the final MooseDocs output. The available configuration items for this extension are provided in Table 1.

Table 1: Configuration items for the comment extension.

KeyDefaultDescription
activeTrueToggle for disabling the extension. This only changes the initial active state, use setActive to control at runtime.

Inline Comments

In order to create inline, or single-line, comments, the !! syntax is available. An example of this is shown below in Example 1.

Example 1: Example usage of inline MooseDocs comments

This is regular text.

!! This is an inline comment.

This is regular text.

Block Comments

In order to create block, or multi-line, comments, the !!! syntax is available. An example of this is shown below in Example 2.

Example 2: Example usage of block MooseDocs comments

This is regular text.

!!!
This is a block comment.
Multiple lines can exist within them.
!!!

This is regular text.

warningwarning:HTML-style block comments are not supported

HTML-style comments with the following syntax:


 <!-- This is an insightful comment. -->

were previously allowed in MooseDown, but were deprecated in 2019 and finally removed in July 2025. The inline and block comment syntax above should be used going forward.