React 应用程序在 localhost 上运行，但在 github 或 heroku 上部署时出错。 部署时没有错误

Question

I create a react app to show corona infection in different countries. This work on my localhost but when i deploy it either on github or on heroku a error generated. below error is given in blockquote. Looking at error when i check file country.js there is no n[0] . please help below is link to hosted app and github repository of the app.

TypeError: "n[0] is undefined" E country.js:13 E country.js:11 React 7 unstable_runWithPriority scheduler.production.min.js:19 React 6 a App.js:22 u runtime.js:45 _invoke runtime.js:274 t runtime.js:97 r asyncToGenerator.js:3 a asyncToGenerator.js:25 react-dom.production.min.js:209:194 React 5 unstable_runWithPriority scheduler.production.min.js:19 React 4 unstable_runWithPriority scheduler.production.min.js:19 React 6 a App.js:22 u runtime.js:45 _invoke runtime.js:274 t runtime.js:97 r asyncToGenerator.js:3 a asyncToGenerator.js:25 TypeError: n[0] is undefined country.js:13:30

​this is link to hosted app on heroku and this is link to app hosted on Github

This is github repository

Answer 1

As stated by Dishant Desai , it is giving a TypeError. In order to fix it, you can change the code in country.js from

const countryflag = Object.keys(data).map((name) => {
    return data[name][0];
})

to

const countryflag = data[0];

And use it directly this way:

${countryflag[country[0]]}

Answer 2

I have checked your site and it gives the following error:

react_devtools_backend.js:6 TypeError: Cannot read property 'Afghanistan' of undefined
    at country.js:13
    at Array.map (<anonymous>)
    at E (country.js:11)
    at Ki (react-dom.production.min.js:153)
    at Fo (react-dom.production.min.js:175)
    at va (react-dom.production.min.js:263)
    at cu (react-dom.production.min.js:246)
    at au (react-dom.production.min.js:246)
    at Za (react-dom.production.min.js:239)
    at react-dom.production.min.js:123

So for that, you have to share the code of that file.