NDEFRecord.toRecords()

The toRecords() method of the NDEFRecord interface converts NDEFRecord.data to a sequence of records based on NDEFRecord.recordType, and returns the result. This allows parsing the payloads of record types which may contain nested records, such as smart poster and external type records.

None.

A list of NDEFRecords.

DOMException "NotSupported"

Indicates that the User Agent does not know how to parse this combination of NDEFRecord.data and NDEFRecord.recordType.

Read an external record with an NDEF message as payload

The example uses external type records to create application-defined records. These records may contain an NDEFMessage as payload, with its own NDEFRecord objects, including local types that are used in the context of the application. Notice that the smart poster record type also contains an NDEF message as payload.

Because NDEF gives no guarantee on the ordering of records, using an external type record with an NDEF message as payload can be useful for encapsulating related data.

This example shows how to read an external record for social posts, which contains an NDEFMessage, containing a text record and a record with the local type "act" (action), with a definition borrowed from smart poster, but used in local application context.

const ndefReader = new NDEFReader();
await ndefReader.scan();
ndefReader.onreading = (event) => {
  const externalRecord = event.message.records.find(
    record => record.type == "example.com:smart-poster"
  );

  let action, text;

  for (const record of externalRecord.toRecords()) {
    if (record.recordType == "text") {
      const decoder = new TextDecoder(record.encoding);
      text = decoder.decode(record.data);
    } else if (record.recordType == ":act") {
      action = record.data.getUint8(0);
    }
  }

  switch (action) {
    case 0: // do the action
      console.log(`Post "${text}" to timeline`);
      break;
    case 1: // save for later
      console.log(`Save "${text}" as a draft`);
      break;
    case 2: // open for editing
      console.log(`Show editable post with "${text}"`);
      break;
  }
};