wavedrom

{ 
  "signal": [ {"name": "CLK", "wave": "p.....|..."},
            {"name":"DAT", "wave":"x.345x|=.x", "data":["A","B","C","D"]},
            {"name": "REQ", "wave": "0.1..0|1.0"},
            {},
            {"name": "ACK", "wave": "1.....|01."}
]
}

Viz

  digraph G {

	subgraph cluster_0 {
		style=filled;
		color=lightgrey;
		node [style=filled,color=white];
		a0 -> a1 -> a2 -> a3;
		label = "process #1";
	}

	subgraph cluster_1 {
		node [style=filled];
		b0 -> b1 -> b2 -> b3;
		label = "process #2";
		color=blue
	}
	start -> a0;
	start -> b0;
	a1 -> b3;
	b2 -> a3;
	a3 -> a0;
	a3 -> end;
	b3 -> end;

	start [shape=Mdiamond];
	end [shape=Msquare];
}

mathjax

When $a \ne 0$, there are two solutions to $(ax^2 + bx + c = 0)$ and they are
$$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$

katex

$$ \int_{a}^{b} x^2 dx $$

JS Sequence Diagram

Title: Here is a title
A->B: Normal line
B-->C: Dashed line
C->>D: Open arrow
D-->>A: Dashed open arrow

flowchartjs

st=>start: Start|past:>http://www.google.com[blank]
e=>end: End|future:>http://www.google.com
op1=>operation: My Operation|past
op2=>operation: Stuff|current
sub1=>subroutine: My Subroutine|invalid
cond=>condition: Yes
or No?|approved:>http://www.google.com
c2=>condition: Good idea|rejected
io=>inputoutput: catch something...|future

st->op1(right)->cond
cond(yes, right)->c2
cond(no)->sub1(left)->op1
c2(yes)->io->e
c2(no)->op2->e

chart

{
    "type": "bar",
    "data": 
       {
        "labels": ["One", "Two", "Three", "Four", "Five", "Six"],
        "datasets": [{
            "label": "# of Votes",
            "data": [12, 19, 3, 5, 3, 8]
        }]
    }
}

Mermaid

graph TD;
  A-->B;
  A-->C;
  B-->D;
  C-->D;