Encoding

// The TextEncoder() constructor does not have any parameters.
const encoder = new TextEncoder();

// encoder.encoding
readonly encoding: string;

encoder.encode(input?: string | undefined): Uint8Array

encoder.encodeInto(input: string, destination: Uint8Array): EncodeIntoResult;

const decoder = new TextDecoder(label?: string | undefined, options?: DecoderOptions | undefined): TextEncoder;

// decoder.encoding
readonly encoding: string;

// decoder.fatal
readonly fatal: boolean;

// decoder.ignoreBOM
readonly ignoreBOM: boolean;

const result = decoder.decode(buffer?: ArrayBuffer | ArrayBufferView | undefined, options?: DecodeOptions | undefined): string;

function handleEvent(event) {
  // Encoder
  const encoder = new TextEncoder();
  const encodeText = encoder.encode('hello world');

  // Decoder
  const decoder = new TextDecoder();
  const decodeText = decoder.decode(encodeText);

  // Response
  const response = new Response(JSON.stringify({
    encodeText: encodeText.toString(),
    decodeText,
  }));

  return response;
}

addEventListener('fetch', (event) => {
  event.respondWith(handleEvent(event));
});