Observable

CVJS December 2019

Michael Holroyd, PhD

@meekohi

meekohi.com

SceneThink

Tools for event organizers

  • Create your event once, promote everywhere. Landing pages, e-mail, ...

Tools for event curators

  • Approve events, full editorial control, create and share content + collections.

SceneThink

Growing partner network

  • Charlottesville: C-VILLE, Charlottesville Tomorrow, WTJU, UVA Arts, Downtown Assoc.
  • Cville, DC, Asheville, Portland, Seattle, Santa Fe, Boston, Eugene, Fort Collins, ...more

@meekohi

@meekohi

@meekohi

@meekohi

@meekohi

@meekohi

Observable

Mike Bostock (d3)

Jeremy Ashkenas (underscore)

 

  • Web-based interactive "Javascript" notebooks.
     
  • Collaborative: fork projects and inline suggestions.
     
  • Reactive cells with automatic data-flow resolution. Like a spreadsheet.

Data

https://observablehq.com/@observablehq/introduction-to-data

  • For small data, inline or attached files are super quick.
     
  • API / ajax is trivial. Secrets can be stored per account.
     
  • Can host raw data on gist.com, etc.
     
  • Direct db access also supported (!)
client = DatabaseClient("Baby Names")

names = client.query(`
SELECT name, gender, year, SUM(number) AS number
FROM names
WHERE year > ?
GROUP BY name, gender, year`, [1920])

"Javascript"

https://observablehq.com/@observablehq/observables-not-javascript

  • Not quite Javascript.
     
  • Cells are separate scripts and implicitly wait for promises.
     
  • yields are bottlenecked to 60fps
     
  • viewof and mutable keywords

 

{
  let i = 0;
  while (true) {
    yield ++i;
  }
}
while (true) {
  context.save();
  context.clearRect(0, 0, width, height);

  for (let i = 0; i < n; ++i) {
    const p = particles[i];
    p.x += p.vx;
    if (p.x < -mD) p.x += width + mD * 2;
    else if (p.x > width + mD) p.x -= width + mD * 2;
    p.y += p.vy;
    if (p.y < -mD) p.y += height + mD * 2;
    else if (p.y > height + mD) p.y -= height + mD * 2;
    p.vx += 0.2 * (Math.random() - .5) - 0.01 * p.vx;
    p.vy += 0.2 * (Math.random() - .5) - 0.01 * p.vy;
    context.beginPath();
    context.arc(p.x, p.y, radius, 0, 2 * Math.PI);
    context.fill();
  }

  context.restore();
  yield context.canvas;
}

Standard Library

https://observablehq.com/@observablehq/standard-library

https://observablehq.com/@observablehq/introduction-to-views

  • viewof connects HTML elements to data.
     
  • KaTeX rendering
     
  • now, width, other helpers
tex.block`
f(x) = \int_{-\infty}^\infty
    \hat f(\xi)\,e^{2 \pi i \xi x}
    \,d\xi
`

How it Runs

Libraries

Don't

Quick Demo

Create a map of all SceneThink locations, pulled directly from the database.


https://observablehq.com/d/035e2bfd3dee0dbb

Thanks

Intro to Observable

By Michael Holroyd

Intro to Observable

Presentation on Observable for the Central Virginia Javascript Meetup, Dec 2019.

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