NDEFReader: scan() method
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
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 read operation is scheduled 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
scan(options) Parameters
optionsOptional-
An object with the following properties:
signal-
An
AbortSignalthat allows cancelling thisscan()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:
AbortErrorDOMException-
Returned if the scan operation was aborted with the
AbortSignalpassed in theoptionsargument. InvalidStateErrorDOMException-
Returned if there's already an ongoing scan.
NotAllowedErrorDOMException-
Returned if the permission for this operation was rejected.
NotSupportedErrorDOMException-
Returned if there is no NFC adapter compatible with Web NFC or a connection cannot 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 # dom-ndefreader-scan |
Browser compatibility
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