Disallow usage of conditional comments (no-conditional-comment)

Microsoft Internet Explorer previously supported using special HTML comments (conditional comments) for targeting specific versions of IE but since IE 10 it is deprecated and not supported in standards mode.

Rule details

Examples of incorrect code for this rule:

<!--[if IE]>
<p>You are using Internet Explorer.</p>
<![endif]-->

<![if !IE]>
<p>You are not using Internet Explorer.</p>
<![endif]>
error: Use of conditional comments are deprecated (no-conditional-comment) at inline:1:1:
> 1 | <!--[if IE]>
    | ^^^^^^^^^^^^
  2 | <p>You are using Internet Explorer.</p>
  3 | <![endif]-->
  4 |


error: Use of conditional comments are deprecated (no-conditional-comment) at inline:3:1:
  1 | <!--[if IE]>
  2 | <p>You are using Internet Explorer.</p>
> 3 | <![endif]-->
    | ^^^^^^^^^^^^
  4 |
  5 | <![if !IE]>
  6 | <p>You are not using Internet Explorer.</p>


error: Use of conditional comments are deprecated (no-conditional-comment) at inline:5:1:
  3 | <![endif]-->
  4 |
> 5 | <![if !IE]>
    | ^^^^^^^^^^^
  6 | <p>You are not using Internet Explorer.</p>
  7 | <![endif]>


error: Use of conditional comments are deprecated (no-conditional-comment) at inline:7:1:
  5 | <![if !IE]>
  6 | <p>You are not using Internet Explorer.</p>
> 7 | <![endif]>
    | ^^^^^^^^^^


4 errors found.