Node Cookbook - Third Edition

Processing infinite amounts of data

Using the data event, we can process the file a small chunk at a time instead, without using a lot of memory. For example, we may wish to count the number of bytes in a file.

Let's create a new folder called infinite-read with a index.js file.

Assuming we are using a Unix-like machine (including macOs and Linux), we can try to tweak this example to count the number of bytes in /dev/urandom. This is an infinite file that contains random data.

Let's write the following into index.js:

const rs = fs.createReadStream('/dev/urandom') var size = 0  rs.on('data', (data) => {   size += data.length   console.log('File size:', size) }) 

Now we can run our program:

$ node index.js 

Notice that the program does not crash, ...