NFC (Near Field Communication)

Functions to interact with NFC (Near Field Communication) tags from your website. You can check whether NFC is available on the device, scan an NFC tag to read its contents (and optionally open the encoded URL in the app), and write data to an NFC tag.

You'll need to import the javascript file in your website before starting from this link.

Platform support: Android and iOS. iOS requires devices with NFC reading capability (iPhone 7 and later) and the appropriate entitlements configured on the app.

Status

Checks the current NFC capability and state of the device — whether NFC hardware is present, whether it is enabled, and whether the app is permitted to use it.

Plain Javascript

window.WTN.NFC.status({
  callback: function (response) {
    console.log(response.status);
  },
});

npm

Parameters:

Key	Type	Required	Description
callback	Function	No	Callback function invoked with the NFC status response.

Callback Response:

Key	Type	Description
type	String	Always "nfcGetStatus".
status	String	Current NFC state. One of "ENABLED", "DISABLED", or "NOT_SUPPORTED".

Status values:

Value	Description
ENABLED	The device has NFC hardware and it is turned on. Ready for scan/write.
DISABLED	The device has NFC hardware but it is currently turned off in settings.
NOT_SUPPORTED	The device does not have NFC hardware.

Read

Starts an NFC scan session. The device waits for an NFC tag to be tapped and returns the tag's contents through the callback. On Android, a system scan dialog is shown (with the configurable message); on iOS, the system NFC scan sheet is presented.

Plain Javascript

window.WTN.NFC.read({
  message: "Hold your device near the NFC tag",
  openUrl: false,
  continuous: false,
  callback: function (response) {
    console.log(response.content);
  },
});

ES5+

Parameters:

Key	Type	Required	Description
message	String	No	The instruction text shown to the user in the system NFC scan dialog.
openUrl	Boolean	No	If true and the scanned tag contains an http/https URL, the app automatically loads it in the WebView. Defaults to false.
continuous	Boolean	No	If true, the callback is kept registered after the first scan so subsequent scans also fire the callback. Defaults to false (single-shot scan).
callback	Function	No	Callback function invoked with the scan response.

Callback Response:

Key	Type	Description
type	String	Always "nfcScanTag".
success	Boolean	true if the tag was read successfully, false if the scan was cancelled or failed.
content	String	The payload read from the tag (URL string, plain text, or other NDEF record content).
opened	Boolean	Present and true only when openUrl was requested, the scan succeeded, and the URL was loaded into the WebView.
error	String	Present when success is false. A short code describing why the scan failed (e.g., user cancellation, unsupported tag).

Example:

window.WTN.NFC.read({
  message: "Scan a product tag",
  openUrl: true,
  callback: function (response) {
    if (response.success) {
      console.log("Tag content:", response.content);
      if (response.opened) {
        console.log("URL was auto-opened in the WebView.");
      }
    } else {
      console.error("NFC scan failed:", response.error);
    }
  },
});

Write

Writes an NDEF message to an NFC tag. The device starts a write session and waits for the user to tap a writable tag against it. Use this to encode a URL, plain text, or a custom MIME payload onto an empty/rewritable NFC tag.

Plain Javascript

window.WTN.NFC.write({
  type: "url",
  content: "https://example.com",
  message: "Hold your device near a writable NFC tag",
  callback: function (response) {
    console.log(response.success);
  },
});

ES5+

Parameters:

Key	Type	Required	Description
type	String	Yes	The type of NDEF record to write. One of "url" or "string".
content	String	Yes	The value to write onto the tag. For type: "url", any valid URI scheme is accepted (http, https, tel, sms, mailto, geo, etc.). For type: "string", any text.
message	String	No	The instruction text shown to the user in the system NFC write dialog.
callback	Function	No	Callback function invoked with the write response.

Supported type values:

Value	Description
url	Writes an NDEF URI record. content should be a valid URI (any scheme).
string	Writes an NDEF text record. content is plain text.

Callback Response:

Key	Type	Description
type	String	Always "nfcWriteTag".
success	Boolean	true if the tag was written successfully, false otherwise.
cancel	Boolean	true if the user cancelled the write session before a tag was tapped. false otherwise.
error	String	Present when success is false. A short error code describing the failure (see the table below).

Possible error values:

Code	Description
INVALID_URL	type was url but content was blank or did not contain a valid URI scheme.
INVALID_MIME_TYPE	A MIME-type write was requested but no mimeType was provided.
WRITE_FAILED	The tag could not be written — e.g., the tag is read-only, locked, or the NDEF payload could not be built.

Example:

window.WTN.NFC.write({
  type: "url",
  content: "https://example.com/product/42",
  message: "Tap a blank NFC tag to encode the product link",
  callback: function (response) {
    if (response.success) {
      console.log("Tag written successfully");
    } else if (response.cancel) {
      console.log("User cancelled the write");
    } else {
      console.error("Write failed:", response.error);
    }
  },
});

Notes:

• Always call status before attempting to read or write so you can show a meaningful message to the user when NFC is DISABLED or NOT_SUPPORTED.

• On iOS, NFC sessions are time-limited by the system; if no tag is tapped within the timeout, the session will end and the callback will fire with success: false.

• openUrl in read only auto-loads http and https URLs into the WebView. Other schemes (e.g., tel:, mailto:) are returned in content but are not opened automatically.

• For write, the tag must be writable and have enough capacity for the NDEF payload. Locked or read-only tags will fail with WRITE_FAILED.