reindex Observable notebook json (see https://gist.github.com/bryangingechen/9d86f1e5ec01674a32dd9c54bdc13947)

reindex-nbjson.js

const fs = require('fs');

const [fileName, outputFile] = process.argv.slice(2);
if (fileName && outputFile) {
  const nodes = JSON.parse(fs.readFileSync(fileName, 'utf8'));
  if (!Array.isArray(nodes))
    return console.log(`${fileName} could not be parsed into an Array`);
  if (nodes.some(d => Object.keys(d).some(e => !['id', 'value', 'pinned'].includes(e))))
    return console.log(`the objects in ${fileName} may only have 'id', 'version' and 'pinned' properties`);
  if (nodes.some(d => d.hasOwnProperty('value') && typeof d.value !== 'string') ||
    nodes.some(d => d.hasOwnProperty('pinned') && typeof d.pinned !== 'boolean'))
    return console.log(`the 'value' and 'pinnned' values in ${fileName}, if present, must be Strings and Booleans, respectively`);
  const newNodes = nodes.reduce((acc, node) => {
    // mutates the elements of nodes, so don't use nodes again after this!
    node.id = acc.length;
    acc.push(node);
    return acc;
  }, []);
  console.log(`${newNodes.length} cells, can be reuploaded as version ${newNodes.length+1}`);
  console.log(`writing to ${outputFile}`);
  fs.writeFileSync(outputFile, JSON.stringify(newNodes), {flag:'wx'});
} else {
  console.log(`run with:
node reindex-nbjson.js inputFile outputFile`);
}