react keys

keys.js

// this is no good because other lists in your app could have the same index
{items.map((item, index) =>
  <div key={index}>
    // ...
  </div>
)}

// This is much better since it will most likely be unique
{items.map((item, index) =>
  <div key={`${item.title}-${index}`}>
    // ...
  </div>
)}

// This is probably the best option
import uuid from 'node-uuid';

{items.map((item) =>
  <div key={uuid()}>
    // ...
  </div>
)}