Each child in an array or iterator should have a unique "key" prop.

[mastershaig]

I'm new to React js and wanted to run 5-redux-react code. But when I clicked Load tweets button, nothing happened and below error on console:

Each child in an array or iterator should have a unique "key" prop. Check the render method of Layout. See https://fb.me/react-warning-keys for more information.

[FelipeBarrosCruz]

I'm fix in my pull request: #45

[mastershaig]

@FelipeBarrosCruz thanks ! But can you explain why it worked before and why this error happened
now?

[willrstern]

I added a comment here https://github.com/learncodeacademy/react-js-tutorials/blob/master/5-redux-react/src/js/actions/tweetsActions.js

Since we load "tweets" from rest.learncode.academy where anyone can update data, sometimes people post bad data that breaks the app...just change the user namespace to something unique and post your own data.

[willrstern]

The unique key isn't a fatal error, just a warning that performance will be slow without a unique key for each item

[mastershaig]

@willrstern thanks !