modern-netcdf/src/browser-worker.js

Modern NetCDF file reader and utilities

// Browser WebWorker implementation for Modern NetCDF
// This file uses ES-module syntax so bundlers can tree-shake it away for Node builds.

import { NetCDFReader } from '..';

let reader = null;

self.onmessage = async (e) => {
  const { id, cmd, payload } = e.data;
  try {
    switch (cmd) {
      case 'open': {
        const { source, options } = payload;
        reader = await NetCDFReader.open(source, options);
        self.postMessage({ id, result: 'ok' });
        break;
      }
      case 'getData': {
        if (!reader) throw new Error('Reader not open');
        const { variable, slice } = payload;
        const data = await reader.getData(variable, slice);
        // Transfer, not copy, the underlying ArrayBuffer when possible.
        const transfer = ArrayBuffer.isView(data) ? [data.buffer] : [];
        self.postMessage({ id, result: data }, transfer);
        break;
      }
      case 'close': {
        if (reader) reader.close();
        reader = null;
        self.postMessage({ id, result: 'closed' });
        break;
      }
      default:
        throw new Error('Unknown command');
    }
  } catch (err) {
    self.postMessage({ id, error: err.message });
  }
};