Build on the map.

Steer an embedded map

Import the client and mount a map. Your page can then move it to a date or a place, show any share link, and hear where the reader has taken it.

<div id="map"></div>
<button id="to-1939" type="button">1 September 1939</button>
<script type="module">
  import { mount } from 'https://rwmqx7dwb5-arch.github.io/IntMap/js/embed-client.js';
  const map = mount('#map', { hash: '#v=22.0000,48.5000,3.30,0,0,f&tt=1914-06-27', height: 450 });
  await map.ready;
  document.querySelector('#to-1939').onclick = () => map.setTime('1939-09-01');
  map.on('state', (s) => console.log(s.state.view, s.state.time, s.link));
</script>

What your page can send

What the map tells your page

The client is a convenience. The protocol is plain postMessage, so a page can also speak it directly:

const frame = document.querySelector('iframe');
const origin = new URL(frame.src).origin;
frame.contentWindow.postMessage(
  { protocol: 'intmap-embed', v: 1, type: 'view', id: '1', lng: 139.69, lat: 35.69, zoom: 9 },
  origin);
window.addEventListener('message', (e) => {
  if (e.source !== frame.contentWindow || e.origin !== origin) return;   // only the map you framed
  if (e.data && e.data.protocol === 'intmap-embed' && e.data.type === 'reply') console.log(e.data.ok, e.data.hash);
});

A command can only change what the frame shows, exactly as a share link can. The frame reports the map’s state — the same link its own “Open in IntMap” button carries — and nothing about the reader, and only to the page that framed it.

Open data

The datasets the map draws, as files you can download, with no key and no rate limit beyond the web host’s. Every address below is a JSON file.

• api/v1/catalog.json

  Every dataset offered for reuse: its files, its size, its licence as its source states it, what that licence requires, the credit to show — and every dataset not offered, with the reason.

• api/v1/countries.json

  The countries (Natural Earth codes, with English and Japanese names), and which datasets say something about each.

• api/v1/countries/JPN.json

  One country: the row every per-country dataset has for it, each with its own dataset’s terms.

• api/v1/embed.json

  The embed address and the message protocol above, as data.

const catalog = await fetch('https://rwmqx7dwb5-arch.github.io/IntMap/api/v1/catalog.json').then((r) => r.json());
const japan = await fetch('https://rwmqx7dwb5-arch.github.io/IntMap/api/v1/countries/JPN.json').then((r) => r.json());
for (const d of catalog.datasets) if (d.terms.credit) console.log(d.id, d.credit.join(' · '));

A dataset is offered only when every source it comes from states a licence that permits redistribution. One that states none, or states terms that are not known to, is listed as not offered rather than offered quietly. Where a dataset combines sources, the strictest condition applies to the whole file.

The borders of a date, shape by shape

In the map, set the clock to a date and open Share, then Cite: it saves the borders drawn on that date as GeoJSON, the whole world or the view. Each feature names its record and row, its dates and who stated them, its identifiers and its licence, read from the catalogue above row by row — a shape whose terms are non-commercial is left out and the file names it, and a shape cut against one keeps its record without its outline.

The datasets, as this build of the site offers them

48 datasets offered for reuse · 50 withheld

Withheld

What you agree to when you reuse