I am a real beginner when it comes to programming. It is my intention to control a device with the API integrated in Google Chrome via the COM port RS485. I try to reproduce the following tutorial: https://web.dev/serial/
The following error message appears in the console:
"Uncaught (in promise) DOMException: Failed to execute 'requestPort' on 'Serial': Must be handling a user gesture to show a permission request."
How can I fix this error?
Thank you very much for your help.
<!DOCTYPE html>
<html lang="de">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>examplepage</title>
<script>
async function caller() {
// Prompt user to select any serial port.
const port = await navigator.serial.requestPort();
// Wait for the serial port to open.
await port.open({ baudRate: 9600 });
};
if ("serial" in navigator) {
alert("Your browser supports Web Serial API!");
caller();
}
else {alert("Your browser does not support Web Serial API, the latest version of Google Chrome is recommended!");};
</script>
</head>
<body>
</body>
</html>The error message "Must be handling a user gesture to show a permission request." means navigator.serial.requestPort() must be called inside a function that responds to a user gesture such as a click.
In your case, it would be something like below.
<button>Request Serial Port</button>
<script>
const button = document.querySelector('button');
button.addEventListener('click', async function() {
// Prompt user to select any serial port.
const port = await navigator.serial.requestPort();
// Wait for the serial port to open.
await port.open({ baudRate: 9600 });
});
</script>
The following code works. I hope it helps others who are interested.
<!DOCTYPE html>
<html lang="de">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>examplepage</title>
<script>
async function start()
{
// Prompt user to select any serial port.
const port = await navigator.serial.requestPort();
// Wait for the serial port to open.
await port.open({ baudRate: 9600 });
}
if ("serial" in navigator) {
alert("Your browser supports Web Serial API!");
}
else {alert("Your browser does not support Web Serial API, the latest version of Google Chrome is recommended!");};
</script>
</head>
<body>
<button onclick="start()">Click me</button>
</body>
</html>