I am trying to connect to the serial port from a web page. I found the Serial API which can support that.

var Serial = {};

(function() {
  'use strict';
  /*
   *
   */
  Serial.debug = true;
  /*
   *
   */
//  Serial.device;
  /*
   *
   */
  Serial.log = function(message) {
    if(Serial.debug)
    {
      let pre;
      if(!document.querySelector('pre'))
      {
        pre = document.createElement('pre');
        document.body.appendChild(pre);
      }
      pre = document.querySelector('pre');
      pre.innerHTML += `\n${message}`;
    }
  }
  /*
   *
   */
  Serial.request = function() {
	  
	  const requestOptions = {
			  // Filter on devices with the Arduino USB vendor ID.
			  filters: [{ vendorId: 0x0403 }],
			};

			// Request an Arduino from the user.
            console.log(navigator);
	        console.log(navigator.serial);
			const port =  navigator.serial.requestPort(requestOptions);

			// Open and begin reading.
			 port.open({ baudrate: 19200 });
			const reader = port.in.getReader();
			while (true) {
			  const {done, data} =  reader.read();
			  if (done) break;
			  console.log(data);
			}
	  
	  

  }
  /*
   *
   */
  Serial.port = {
    /*
     *
     */
     device:{},
    /*
     *
     */
     connect:function()
     {
      let loop = () => {
        this.device.transferIn(5, 64).then(result => {
        	Serial.log(result);
          loop();
        }, error => {
          WebUSB.log(error);
        });
      }
      console.log(this.device);
      return this.device.open( {baudrate: 19200 })
        .then(() => this.device.selectConfiguration(1))
        .then(() => this.device.claimInterface(1))
        .then(() => this.device.controlTransferOut({requestType: 'class', recipient: 'interface', request: 0x22, value: 0x01, index: 0x02}))
        .then(() => {loop})
        .then(
          result => {
        	  Serial.log('successfull');
          }
        )
        .catch(
          error => {
        	  Serial.log(error);
          }
        );
    },
    /*
     *
     */
    send:function()
    {
      let d = new Date();
      let h = d.getHours();
      let m = d.getMinutes();
      let s = d.getSeconds();
      if(h < 10){h = `0${h}`};
      if(m < 10){m = `0${m}`};
      if(s < 10){s = `0${s}`};
      let data = `show time ${h}${s % 2 == 1 ? ':' : ' '}${m}${s % 2 == 0 ? ':' : ' '}${s}`;
      console.log(data);
      let textEncoder = new TextEncoder();
      WebUSB.port.device.transferOut(4, textEncoder.encode(data));
    },
    /*
     *
     */
     disconnect:function()
     {
      console.log(Serial.port.device)
      Serial.port.device.close()
      .then(
        result => {
        	Serial.log('closed');
          document.querySelectorAll('button')[1].parentNode.removeChild(document.querySelectorAll('button')[1]);
        }
      )
      .catch(
        error => {
        	Serial.log(error);
        }
      );;
     }
   }

})();

/*
 *
 */
window.addEventListener('DOMContentLoaded', connect => {
  let button = document.createElement('button');
  button.innerHTML = 'Connect a USB Device';
  button.addEventListener('click', Serial.request);
  document.body.appendChild(button);
}, true);

I am trying to connect to the serial port from a web page. I found the Serial API which can support that.

var Serial = {};

(function() {
  'use strict';
  /*
   *
   */
  Serial.debug = true;
  /*
   *
   */
//  Serial.device;
  /*
   *
   */
  Serial.log = function(message) {
    if(Serial.debug)
    {
      let pre;
      if(!document.querySelector('pre'))
      {
        pre = document.createElement('pre');
        document.body.appendChild(pre);
      }
      pre = document.querySelector('pre');
      pre.innerHTML += `\n${message}`;
    }
  }
  /*
   *
   */
  Serial.request = function() {
	  
	  const requestOptions = {
			  // Filter on devices with the Arduino USB vendor ID.
			  filters: [{ vendorId: 0x0403 }],
			};

			// Request an Arduino from the user.
            console.log(navigator);
	        console.log(navigator.serial);
			const port =  navigator.serial.requestPort(requestOptions);

			// Open and begin reading.
			 port.open({ baudrate: 19200 });
			const reader = port.in.getReader();
			while (true) {
			  const {done, data} =  reader.read();
			  if (done) break;
			  console.log(data);
			}
	  
	  

  }
  /*
   *
   */
  Serial.port = {
    /*
     *
     */
     device:{},
    /*
     *
     */
     connect:function()
     {
      let loop = () => {
        this.device.transferIn(5, 64).then(result => {
        	Serial.log(result);
          loop();
        }, error => {
          WebUSB.log(error);
        });
      }
      console.log(this.device);
      return this.device.open( {baudrate: 19200 })
        .then(() => this.device.selectConfiguration(1))
        .then(() => this.device.claimInterface(1))
        .then(() => this.device.controlTransferOut({requestType: 'class', recipient: 'interface', request: 0x22, value: 0x01, index: 0x02}))
        .then(() => {loop})
        .then(
          result => {
        	  Serial.log('successfull');
          }
        )
        .catch(
          error => {
        	  Serial.log(error);
          }
        );
    },
    /*
     *
     */
    send:function()
    {
      let d = new Date();
      let h = d.getHours();
      let m = d.getMinutes();
      let s = d.getSeconds();
      if(h < 10){h = `0${h}`};
      if(m < 10){m = `0${m}`};
      if(s < 10){s = `0${s}`};
      let data = `show time ${h}${s % 2 == 1 ? ':' : ' '}${m}${s % 2 == 0 ? ':' : ' '}${s}`;
      console.log(data);
      let textEncoder = new TextEncoder();
      WebUSB.port.device.transferOut(4, textEncoder.encode(data));
    },
    /*
     *
     */
     disconnect:function()
     {
      console.log(Serial.port.device)
      Serial.port.device.close()
      .then(
        result => {
        	Serial.log('closed');
          document.querySelectorAll('button')[1].parentNode.removeChild(document.querySelectorAll('button')[1]);
        }
      )
      .catch(
        error => {
        	Serial.log(error);
        }
      );;
     }
   }

})();

/*
 *
 */
window.addEventListener('DOMContentLoaded', connect => {
  let button = document.createElement('button');
  button.innerHTML = 'Connect a USB Device';
  button.addEventListener('click', Serial.request);
  document.body.appendChild(button);
}, true);

But the navigator.serial.requestPort() call is failing; I find that the navigator.serial is undefined. I'm pretty sure the serial port is connected to my puter. Are functions on navigator.serial and SerialPort in Serial API unimplemented? My chrome version is 74.0.3729.131. My system is Ubuntu 16.04

• javascript
• google-chrome
• webusb

Share Improve this question Follow edited Aug 21, 2019 at 22:06 BenMorel 36.8k5252 gold badges206206 silver badges337337 bronze badges asked May 14, 2019 at 8:48 Ziheng booker WangZiheng booker Wang 3311 silver badge33 bronze badges 1

• Now available on Chrome 77 beta, under chrome://flags/#enable-experimental-web-platform-features. – BenMorel Commented Aug 21, 2019 at 22:08

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2 Answers 2

Sorted by: Reset to default 3

Posting @Benjamin 's answer for the sake of clarity. Serial port connection's are still an "experimental" feature in Chrome early 2020. You have to turn on the following option:

chrome://flags/#enable-experimental-web-platform-features

Just copy paste that line in the Chrome address bar and enable it.

The Serial API is not yet pletely implemented in Chrome. I see that you have already found the issue in the Chromium bug tracker for the implementation. Updates on implementation progress will be posted there. It is currently in the "started" state, not "fixed".