NDEFReader.scan()

Draft: This page is not complete.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The scan() method of the NDEFReader interface activates a reading device and returns a Promise that either resolves when an NFC tag is read or rejects if a hardware or permission error is encountered. This method triggers a permission prompt if the "nfc" permission has not been previously granted.

Syntax

var readerPromise = NDEFReader.scan(options);

Parameters

options Optional

An object with the following properties:

  • signal -- An AbortSignal that allows cancelling this scan() operation.

Return value

A Promise that resolves immediately after scheduling read operations for the NFC adapter.

Exceptions

This method doesn't throw exceptions; instead, it rejects the returned promise, passing a DOMException whose name is one of the following:

"AbortError"

The scan operation was aborted with the AbortSignal passed in the options argument.

"InvalidStateError"

There's already an ongoing scan.

"NotAllowedError"

The permission for this operation was rejected.

"NotSupportedError"

There is no NFC adapter compatible with Web NFC, or a connection can not be established.

Examples

Handle scanning errors

This example shows what happens when a scan promise rejects and readingerror is thrown.

const ndef = new NDEFReader();
ndef.scan().then(() => {
  console.log("Scan started successfully.");
  ndef.onreadingerror = (event) => {
    console.log("Error! Cannot read data from the NFC tag. Try a different one?");
  };
  ndef.onreading = (event) => {
    console.log("NDEF message read.");
  };
}).catch(error => {
  console.log(`Error! Scan failed to start: ${error}.`);
});

Specifications

Specification
Web NFC API
# dom-ndefreader-scan

Browser compatibility

BCD tables only load in the browser