Basic inference of JSON Schema from a JSON object

json_to_json_schema.js

const c = require('/usr/local/lib/node_modules/clipboardy');

const resolve = (value) =>
  Array.isArray(value)
    ? { type: 'array', items: resolve(value[0]) }
    : typeof value === 'object'
    ? {
        type: 'object',
        properties: Object.fromEntries(
            Object.entries(value).map(([key, value]) => [key, resolve(value)])
          ),
      }
    : { type: typeof value, example: value };

const defaultOffset = '  ';
const format = (value, offset = '') =>
  `${Object.entries(value)
    .map(
        ([key, value]) =>
          `${offset}${key}:${
              typeof value === 'object'
                ? `\n${format(value, `${offset}${defaultOffset}`)}`
                : ` ${value}`
            }`
      )
    .join('\n')}`;

// Takes source from clipboard and writes back into clipboard
const run = ()=>c.writeSync(
  format(
    resolve(
      JSON.parse(
        c.readSync()
      )
    )
  )
);

run();