code-boxx/0-JS-NFC.MD

## 0-JS-NFC.MD

      
    Raw
  

              0-JS-NFC.MD
            
          
    JAVASCRIPT READ & WRITE NFC TAGS

https://code-boxx.com/read-write-nfc-javascript/
NOTES


Take note that https:// and access permission is required for Web NFC to work properly.
Web NFC is still in the experimental phase at the time of writing. It is only supported on a few browsers, and it may change over time.

LICENSE

Copyright by Code Boxx
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

  
## 1-read-write.html
<!DOCTYPE html>
<html>
  <head>
    <title>Web NFC Read Write</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
    <link rel="stylesheet" href="x-dummy.css">
    <script defer src="1-read-write.js"></script>
  </head>
  <body>
    <!-- (A) NFC TAG ACTIONS -->
    <div id="demoNFC">
      <input type="text" id="demoT" value="Hello World" required>
      <input type="button" id="demoW" value="Write" disabled onclick="nfc.write();">
      <input type="button" id="demoR" value="Read" disabled onclick="nfc.read()">
    </div>

    <!-- (B) "CONSOLE MESSAGES" -->
    <div id="demoMSG"></div>
  </body>
</html>

## 1-read-write.js
var nfc = {
  // (A) INIT
  hTxt : null, // html data to write
  hWrite : null, // html write button
  hRead : null, // html read button
  hMsg : null, // html "console messages"
  init : () => {
    // (A1) GET HTML ELEMENTS
    nfc.hTxt = document.getElementById("demoT"),
    nfc.hWrite = document.getElementById("demoW"),
    nfc.hRead = document.getElementById("demoR"),
    nfc.hMsg = document.getElementById("demoMSG");

    // (A2) FEATURE CHECK + GET PERMISSION
    if ("NDEFReader" in window) {
      nfc.logger("Ready");
      nfc.hWrite.disabled = false;
      nfc.hRead.disabled = false;
      nfc.hReadOnly.disabled = false;
    } else { nfc.logger("Web NFC is not supported on this browser."); }
  },

  // (B) HELPER - DISPLAY LOG MESSAGE
  logger : msg => {
    let row = document.createElement("div");
    row.innerHTML = msg;
    nfc.hMsg.appendChild(row);
  },

  // (C) WRITE NFC TAG
  write : () => {
    nfc.logger("Approach NFC Tag");
    const ndef = new NDEFReader();
    ndef.write(nfc.hTxt.value)
    .then(() => nfc.logger("Write OK"))
    .catch(err => nfc.logger("ERROR - " + err.message));
  },

  // (D) READ NFC TAG
  read : () => {
    nfc.logger("Approach NFC Tag");
    const ndef = new NDEFReader();
    ndef.scan()
    .then(() => {
      ndef.onreadingerror = err => nfc.logger("Read failed");
      ndef.onreading = evt => {
        const decoder = new TextDecoder();
        for (let record of evt.message.records) {
          nfc.logger("Record type: " + record.recordType);
          nfc.logger("Record encoding: " + record.encoding);
          nfc.logger("Record data: " + decoder.decode(record.data));
        }
      };
    })
    .catch(err => nfc.logger("Read error - " + err.message));
  }
};
window.onload = nfc.init;

## 2-write-types.js
ndef.write({
  records: [
    { recordType:"text", data:"Hello World" },
    { recordType:"url", data:"https://code-boxx.com/" },
    { recordType:"url", data:"sms:12345678" },
    { recordType:"url", data:"tel:12345678" },
    { recordType:"url", data:"mailto:jon@doe.com?subject=Title&body=Body" },
    { recordType:"url", data:"geo:35.698723,139.772639" },
    { recordType:"empty" }
  ]
})
.then(() => nfc.logger("Write OK"))
.catch(err => nfc.logger("ERROR - " + err.message));

## 3-read-only.js
const ndef = new NDEFReader();
ndef.makeReadOnly()
.then(() => nfc.logger("Tag is now read only."))
.catch(err => nfc.logger("ERROR - " + err.message));

## x-dummy.css
/* (X) NOT IMPORTANT */
* {
  font-family: Arial, Helvetica, sans-serif;
  box-sizing: border-box;
  font-size: 1rem;
}
body, input, #demoNFC, #demoMSG { padding: 10px; }
body { max-width: 600px; }
#demoNFC {
  display: flex;
  margin-bottom: 10px;
  border: 1px solid #e7e7e7;
  background: #f3f3f3;
}
#demoT { flex-grow: 1; }
input {
  padding: 10px;
  border: 0;
}
input[type=button] {
  margin: 0 1px;
  color: #fff;
  background: #225cc5;
  cursor: pointer;
}
input[type=button]:disabled {
  color: #7c7c7c;
  background: #c3c3c3;
}
#demoMSG {
  border: 1px solid #e7e7e7;
  background: #fff;
}
	<!DOCTYPE html>
	<html>
	<head>
	<title>Web NFC Read Write</title>
	<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
	<link rel="stylesheet" href="x-dummy.css">
	<script defer src="1-read-write.js"></script>
	</head>
	<body>
	<!-- (A) NFC TAG ACTIONS -->
	<div id="demoNFC">
	<input type="text" id="demoT" value="Hello World" required>
	<input type="button" id="demoW" value="Write" disabled onclick="nfc.write();">
	<input type="button" id="demoR" value="Read" disabled onclick="nfc.read()">
	</div>

	<!-- (B) "CONSOLE MESSAGES" -->
	<div id="demoMSG"></div>
	</body>
	</html>
	var nfc = {
	// (A) INIT
	hTxt : null, // html data to write
	hWrite : null, // html write button
	hRead : null, // html read button
	hMsg : null, // html "console messages"
	init : () => {
	// (A1) GET HTML ELEMENTS
	nfc.hTxt = document.getElementById("demoT"),
	nfc.hWrite = document.getElementById("demoW"),
	nfc.hRead = document.getElementById("demoR"),
	nfc.hMsg = document.getElementById("demoMSG");

	// (A2) FEATURE CHECK + GET PERMISSION
	if ("NDEFReader" in window) {
	nfc.logger("Ready");
	nfc.hWrite.disabled = false;
	nfc.hRead.disabled = false;
	nfc.hReadOnly.disabled = false;
	} else { nfc.logger("Web NFC is not supported on this browser."); }
	},

	// (B) HELPER - DISPLAY LOG MESSAGE
	logger : msg => {
	let row = document.createElement("div");
	row.innerHTML = msg;
	nfc.hMsg.appendChild(row);
	},

	// (C) WRITE NFC TAG
	write : () => {
	nfc.logger("Approach NFC Tag");
	const ndef = new NDEFReader();
	ndef.write(nfc.hTxt.value)
	.then(() => nfc.logger("Write OK"))
	.catch(err => nfc.logger("ERROR - " + err.message));
	},

	// (D) READ NFC TAG
	read : () => {
	nfc.logger("Approach NFC Tag");
	const ndef = new NDEFReader();
	ndef.scan()
	.then(() => {
	ndef.onreadingerror = err => nfc.logger("Read failed");
	ndef.onreading = evt => {
	const decoder = new TextDecoder();
	for (let record of evt.message.records) {
	nfc.logger("Record type: " + record.recordType);
	nfc.logger("Record encoding: " + record.encoding);
	nfc.logger("Record data: " + decoder.decode(record.data));
	}
	};
	})
	.catch(err => nfc.logger("Read error - " + err.message));
	}
	};
	window.onload = nfc.init;
	ndef.write({
	records: [
	{ recordType:"text", data:"Hello World" },
	{ recordType:"url", data:"https://code-boxx.com/" },
	{ recordType:"url", data:"sms:12345678" },
	{ recordType:"url", data:"tel:12345678" },
	{ recordType:"url", data:"mailto:jon@doe.com?subject=Title&body=Body" },
	{ recordType:"url", data:"geo:35.698723,139.772639" },
	{ recordType:"empty" }
	]
	})
	.then(() => nfc.logger("Write OK"))
	.catch(err => nfc.logger("ERROR - " + err.message));
	const ndef = new NDEFReader();
	ndef.makeReadOnly()
	.then(() => nfc.logger("Tag is now read only."))
	.catch(err => nfc.logger("ERROR - " + err.message));
	/* (X) NOT IMPORTANT */
	* {
	font-family: Arial, Helvetica, sans-serif;
	box-sizing: border-box;
	font-size: 1rem;
	}
	body, input, #demoNFC, #demoMSG { padding: 10px; }
	body { max-width: 600px; }
	#demoNFC {
	display: flex;
	margin-bottom: 10px;
	border: 1px solid #e7e7e7;
	background: #f3f3f3;
	}
	#demoT { flex-grow: 1; }
	input {
	padding: 10px;
	border: 0;
	}
	input[type=button] {
	margin: 0 1px;
	color: #fff;
	background: #225cc5;
	cursor: pointer;
	}
	input[type=button]:disabled {
	color: #7c7c7c;
	background: #c3c3c3;
	}
	#demoMSG {
	border: 1px solid #e7e7e7;
	background: #fff;
	}