Data: Blob, FormData, URL, Text Encoding and Streams

There are these standard globals, which behave as in browsers:

• Blob, File: immutable bytes with a MIME type. URL.createObjectURL(blob) makes a blob:null/… address that fetch, XMLHttpRequest and the src of CanvasImage, Image and Video can load, so three.js's GLTFLoader reads the textures embedded in a GLB. As in browsers, the address is valid until URL.revokeObjectURL() or until the content stops; images and videos already loaded aren't affected by revoking it.
• FormData: form fields and files, sent as multipart/form-data as a request body; response.formData() parses it too. There are no form elements, so new FormData(form) throws.
• URL, URLSearchParams: parsed by the WHATWG URL standard. International domain names are converted to Punycode, but without the full UTS #46 mapping table, so domains with a few special characters may come out differently from browsers.
• TextEncoder, TextDecoder: UTF-8 and UTF-16 are exactly as in browsers. TextDecoder also has the legacy encodings of the Encoding standard (GBK, gb18030, Big5, Shift_JIS, EUC-JP, EUC-KR, windows-125x, ISO-8859-x, KOI8 and more), decoded by the system, where a few characters and the replacement of bad bytes may differ slightly from browsers. TextEncoderStream and TextDecoderStream work on streams.
• Streams: ReadableStream (byte streams and BYOB readers, for await, ReadableStream.from() included), WritableStream, TransformStream and the two queuing strategies, from web-streams-polyfill.
• MessageEvent, CloseEvent and ProgressEvent are global too, as are Event and EventTarget, and the global object is also self (three.js and other libraries use self.URL).

// Parse newline-delimited JSON while it downloads
const response = await fetch('https://example.com/events.ndjson');
let buffer = '';
for await (const text of response.body.pipeThrough(new TextDecoderStream())) {
  buffer += text;
  const lines = buffer.split('\n');
  buffer = lines.pop();
  for (const line of lines) if (line) handle(JSON.parse(line));
}

// Upload a file and a field
const form = new FormData();
form.append('title', 'Screenshot');
form.append('file', new Blob([bytes], { type: 'image/png' }), 'shot.png');
await fetch('https://example.com/upload', { method: 'POST', body: form });