how can i render mermaid in slides?

I used mermaid in markdown, like:

sequenceDiagram
   participant A
   participant B
   A -> B: test

It can be render well in markdown preview, but it just shown as original code not a diagram in the slides. How can i do to make the presentation support mermaid in markdown?

[rvion]

how can we enter newer mermaid diagrams such as https://mermaid-js.github.io/mermaid/#/gantt?id=syntax ?

it doesn’t seem to work

gantt
    dateFormat  YYYY-MM-DD
    title Adding GANTT diagram functionality to mermaid

    section A section
    Completed task            :done,    des1, 2014-01-06,2014-01-08
    Active task               :active,  des2, 2014-01-09, 3d
    Future task               :         des3, after des2, 5d
    Future task2              :         des4, after des3, 5d

    section Critical tasks
    Completed task in the critical line :crit, done, 2014-01-06,24h
    Implement parser and jison          :crit, done, after des1, 2d
    Create tests for parser             :crit, active, 3d
    Future task in critical line        :crit, 5d
    Create tests for renderer           :2d
    Add to mermaid                      :1d

    section Documentation
    Describe gantt syntax               :active, a1, after des1, 3d
    Add gantt diagram to demo page      :after a1  , 20h
    Add another diagram to demo page    :doc1, after a1  , 48h

    section Last section
    Describe gantt syntax               :after doc1, 3d
    Add gantt diagram to demo page      :20h
    Add another diagram to demo page    :48h

[fuhrmanator]

@evilz OK, I got the jest tests to pass, but it seems the extension still has the vscode dependency. Would you agree to migrate it per this explanation?