cors-issue.md

This code works correctly in Postman, but it does not work in my app, nor using this same structure in the code nor the getJson() custom function we learned to use in the class.

var myHeaders = new Headers();
myHeaders.append("Content-Type", "application/json");
myHeaders.append("X-MBX-APIKEY", "W4wBtjQxbUWdDiRak0kC6mbIi28zYCmghxIa6vUTUWljNilQA766nHH9RN6I1tpf");

var requestOptions = {
  method: 'POST',
  headers: myHeaders,
  redirect: 'follow'
};

fetch("https://testnet.binance.vision/api/v3/userDataStream", requestOptions)
  .then(response => response.text())
  .then(result => console.log(result))
  .catch(error => console.log('error', error));

I've also added/removed some of the previous and following lines to the code, without success:

myHeaders.append("X-MBX-APIKEY", "W4wBtjQxbUWdDiRak0kC6mbIi28zYCmghxIa6vUTUWljNilQA766nHH9RN6I1tpf");
myHeaders.append('Access-Control-Allow-Origin', 'http://127.0.0.1:3002');
myHeaders.append('Access-Control-Allow-Methods', 'POST');
myHeaders.append('Access-Control-Allow-Headers', 'Content-Type, Authorization');
myHeaders.append('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
myHeaders.append('mode', 'no-cors');

This is the error I'm getting (one of the many I've seen).

Access to fetch at 'https://testnet.binance.vision/api/v3/userDataStream' from origin 'http://127.0.0.1:3000'
has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers
in preflight response.

Possible solution(s): https://stackoverflow.com/questions/43262121/trying-to-use-fetch-and-pass-in-mode-no-cors

I'm working on some of those, especially:

• https://stackoverflow.com/a/54390080/7389293
• https://stackoverflow.com/a/43268098/7389293

As by now, Here's my project: https://github.com/carloswm85/carloswm85.github.io/blob/223969948239f21f497c09aa55a74a66e13bb5e1/portfolio/college-projects/f_2021-wdd330/projects/project02_binance-orders/src/main.js