files/en-us/web/api/ndefreader/reading_event/index.md
{{SecureContext_Header}}{{SeeCompatTable}}{{APIRef("Web NFC API")}}
The reading event of the {{DOMxRef("NDEFReader")}} interface is fired whenever a new reading is available from compatible NFC devices (e.g., NFC tags supporting NDEF) when these devices are within the reader's magnetic induction field.
Use the event name in methods like {{domxref("EventTarget.addEventListener", "addEventListener()")}}, or set an event handler property.
addEventListener("reading", (event) => { })
onreading = (event) => { }
A generic {{domxref("Event")}}.
The following example shows how to process events using both the onreading and onreadingerror event handlers.
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}}
{{Compat}}