[Yahoo | GANGA] HTML comments partially removed

[husseinalhammad]

I initially ran into this on Yahoo (web and Android), but upon further testing I found a similar behaviour on Gmail Android with a non-Gmail account.

Both Yahoo and Gmail attempt to remove HTML comments. However, Yahoo partially removes HTML comments if -> (single dash) is within the comment, while GANGA (Android) partially removes HTML comments if 2 occurrences of -> is within the comment. This happens even if the HTML comment is technically valid.

HTML comments syntax

https://html.spec.whatwg.org/multipage/syntax.html#comments

Optionally, text, with the additional restriction that the text must not start with the string ">", nor start with the string "->", nor contain the strings "", or "--!>", nor end with the string "<!-".

Yahoo

The following is a valid HTML comment, however Yahoo assumes it ends at ->:

<!--
  some comment -> text starting here is visible on Yahoo
-->

GANGA

The following is also a valid HTML comment, however GANGA (Android at least) assumes it ends at the second ->:

<!--
  another comment -> here -> text starting here is visible on GANGA
-->

[M-J-Robbins]

Oh wow this is really cool so we can use conditional comments for Yahoo and GANGA

<!--Yahoo-> 
<p style="background:red;color:white;font-size:50px;">You are using Yahoo or AOL</p>
<!yahoo-->

<!--Yahoo-GANGA-> 
<p style="background:green;color:white;font-size:50px;">You are using Yahoo, AOL or GANGA</p>
<!yahoo-GANGA-->

(the - between Yahoo and GANGA here is what's making it work).

<!--GANGA->
<div style="display:none"> -> 
<p style="background:green;color:white;font-size:50px;">GANGA</p>
<!GANGA--><!--</div><! -->

[husseinalhammad]

@M-J-Robbins I was annoyed when I ran into this, but I like how you turned this into "we can now use this to target these clients"!

[matthieuSolente]

Your discovery allows me to swap image even for yahoo-Ganga, which is a little revolution for me !! haha..https://codepen.io/matthieuSolente/pen/vYmKyZe thanks guys !!