I am using heroku to test my application. how to solve cors problem?

Question

Error: I am using heroku to test my application. Back (node.js - express) frontend written in react

When entering the site, an error occurs when receiving data

How to deal with it

Access to fetch at 'my-web_api/allCity' from origin 'my-web_api' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

Answer 1

You have to install cors(Cross-Origin Resource Sharing) package to avoid this type of error

npm i cors

and use it in your server.js file just like that

 const cors = require('cors')
 app.use(cors())