Function getTextDecoder

packages/common/http/src/fetch.ts:484–497

* Creates a `TextDecoder` instance using the charset extracted from the `Content-Type` header, * falling back to the default (`utf-8`) if no valid charset is specified or supported.

(contentType: string)

 * falling back to the default (`utf-8`) if no valid charset is specified or supported.
 */
function getTextDecoder(contentType: string): TextDecoder {
  const match = contentType.match(CHARSET_REGEX);
  if (match !== null) {
    try {
      return new TextDecoder(match[1]);
    } catch {
      // Catching `RangeError` thrown by `new TextDecoder(...)` when the encoding label is invalid or
      // unsupported. There is no synchronous inspection API on `TextDecoder` to verify whether an
      // encoding is supported without executing the constructor, so catching the error is required
      // before falling back to default UTF-8.
    }
  }
  return new TextDecoder();
}