Element-web: Markdown strike-through

[pacien]

Is your suggestion related to a problem? Please describe.

Markdown formatting should support strike-through with ~~.

Using HTML tags is both unintuitive and inconvenient. Friends coming from Discord or Github users now expect most Markdown formatting to work and are heavily frustrated by the partial support. We always get bitten by this small discrepancy and have to edit messages afterwards.

Describe the solution you'd like

Allow the use of ~~ to strike text through: ~~some text~~ should be rendered as some text.

Describe alternatives you've considered

HTML tags such as <del>, <s> and their closing counterparts are annoying to type in the middle of conversations. That's why we have Markdown instead of HTML or BBCode in the first place for italic and bold text.

Switching from Markdown to the formatting toolbar back and forth solely to strike text through is cumbersome too.

Additional context

The CommonMark library used by Riot doesn't support ~~ by default, but some extensions seem to exist to fill that gap.

Related issue: https://github.com/vector-im/riot-web/issues/9330

[turt2live]

as you've noted in the issue, we use commonmark and this is a limitation of that. Will leave this open to track the request given this and 9330 aren't the first issues to complain about this...

[SaphireLattice]

Perhaps it would be a good idea to switch from CommonMark to a different Markdown parsing library that supports GitHub flavoured markdown, one of the most commonly used markdown variations?

[t3chguy]

@SaphireLattice that's https://github.com/vector-im/riot-web/issues/5940

[aaronraimist]

This doesn't need an old-composer label