features = {
// build an array of features as they are parsed from the stream
const f = [];
for await (const newFeatures of streamGeoJSONL(url)) {
f.push(...newFeatures);
yield f;
}
}
async function* streamGeoJSONL(url) {
const response = await fetch(url);
console.log(response.redirected)
const reader = response.body.getReader(); // stream reader
const decoder = new TextDecoder('utf-8'); // for decoding binary stream data into strings
let lineFragment = ''; // incomplete line fragment from previous stream chunk
while (true) {
// get next stream chunk
const { done, value } = await reader.read();
if (!done) {
// decode buffer into string, and split into lines
const lines = decoder.decode(value).split('\n');
// if we have a line fragment from the previous chunk, prepend it to the first new line
if (lineFragment != '') {
lines[0] = lineFragment + lines[0];
lineFragment = '';
}
// if the last line isn't complete (doesn't end in a newline), save it as a fragment for next chunk
const lastLine = lines[lines.length-1];
if (lastLine[lastLine.length-1] !== '\n') {
lineFragment = lines.pop();
}
// parse and return new features
yield lines.map(JSON.parse);
}
else {
break; // done processing stream
}
}
}
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.