Buffer

In the context of React JS, the term "Buffer" doesn't directly refer to a specific concept within the React library.

However, buffering is a general concept in programming that can have relevance to a React application if you're dealing with data streaming, file transfers, or any sort of asynchronous data handling operations. A buffer is a temporary storage place in memory where data can be placed before it is processed.

If you had a React component that reads data from a file in chunks, for example, you might have a buffer in your Express server which collects these chunks before the whole file is on the server. Here's how you might use a buffer in a Node.js backend that supports your React application:

```javascript
const fs = require('fs');

const readStream = fs.createReadStream('./file.txt');
let buffer = Buffer.alloc(0);

readStream.on('data', chunk => {
buffer = Buffer.concat([buffer, chunk]);
});

readStream.on('end', () => {
console.log('Received data:', buffer.toString());
});
```

In this code example, we're reading a file from the filesystem in chunks. With each data event from the stream, we're adding to our buffer. When the stream ends, we log the contents of the buffer, which will be the full contents of the file.

Also, keep in mind that Buffer functionality is more pertinent to backend Node.js, not React.js. React.js is a UI library for building user interfaces and does not directly interact with buffers. However, you may encounter them in context with asynchronous interactions, server requests or similar scenarios while working with React.js.