XMLHttpRequest PUT request is blocked by CORS policy

Need Help With My Project
1

Hello,
I’m trying to send data to my Arduino UNO. The GET method works perfectly fine, but the PUT method returns ‘has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: It does not have HTTP ok status.’ error.

This is an XMLHttpRequest in HTML.

    var request = new XMLHttpRequest();
    request.open('PUT', 'http://blynk-cloud.com/xxxxxxx/update/V0');
    request.setRequestHeader('Content-Type', 'application/json');
    request.onreadystatechange = function () {
      if (this.readyState === 4) {
        console.log('Status:', this.status);
        console.log('Headers:', this.getAllResponseHeaders());
        console.log('Body:', this.responseText);
      }
    };

    var body = [
      255,
      0,
      0
    ];

    request.send(JSON.stringify(body));

Thank you

2

Any reason why you don’t stick with the GET method? Is more reliable in my experience anyway.

Pete.

3

But I need to send 3 numbers…red, green and blue values. How can I send it with GET? In my arduino project I’m using as for example
int r = params[0].asInt();

4

Have you read the API documentation?

Pete.

5

Yes…GET method can send one value

6

you can send multiple values…

http://blynk-cloud.com/xxxxxxx/update/V1?value=50&value=100&value=150

Pete.

7

Ohhh, thank you. I don’t know about that.