Math

createNodeConverter() enables display-math parsing by default, so a $$ block needs no configuration:

Compare $200/mo versus $350/mo before you read the integral.

$$
\int_0^1 x^2\,dx = \frac{1}{3}
$$

A $$ block becomes an image. Single dollars are left alone by default, so the prices survive. Recorded from a real slackmark-node run rather than produced live, so the picture is the renderer's own PNG.

Block Kit JSON

Chromium cannot run in a browser, so this figure replays a committed recording of a real createNodeConverter() run (slackmark-node with KaTeX 0.18.1, Chromium via puppeteer 25.3.0). Regenerate it with pnpm docs:raster-examples. The picture is painted from PNG bytes committed to this repo (348×184, 6.6 kB, renderer bytes), substituted for the payload's image reference because a browser cannot fetch it. A capturing stub stood in for the Slack uploader, so the slack_file IDs below are synthetic; a real upload returns workspace file IDs. Nothing else was touched: the JSON below is what convert() returned.

[
  {
    "type": "rich_text",
    "elements": [
      {
        "type": "rich_text_section",
        "elements": [
          {
            "type": "text",
            "text": "Compare $200/mo versus $350/mo before you read the integral."
          }
        ]
      }
    ]
  },
  {
    "type": "image",
    "alt_text": "display math",
    "slack_file": {
      "id": "F09DOCS0001"
    }
  }
]

Single-dollar inline math is off by default, so Compare $200/mo versus $350/mo keeps both dollar signs. Set enableInlineMath: true to read $x^2$ as math; it stays code-styled text either way, because rasterizing inline formulas would break sentence flow. Only display math becomes an image.

The built-in KatexRenderer loads KaTeX JavaScript, CSS, and fonts from installed package bytes, renders inside the isolated browser context, checks dimensions, and returns a PNG. It runs with trust: false, bounded macro expansion, bounded source, and bounded element size. When a formula is invalid or hits one of those limits, the Slack result keeps readable TeX and picks up a structured degradation.

For font size, padding, background, and limits, see Built-in renderers.