What is Input-Output Model (I-O) in Nodejs

In the next video, you will learn what the I/O model is and also understand the difference between the blocking I/O model and the non-blocking I/O model.

In the last video, you learnt that JavaScript is a single-threaded language, i.e., it has only one thread. So, you cannot afford to have the blocking I/O model. This model is undesirable when there are a lot of time-consuming long-running tasks. This requires a model in which one code does not block other parts of the code.

In the following video, you will look at the non-blocking I/O model in action in the context of the example from the previous video.

In the last video, you learnt the following facts:

1. Node.js uses an event-driven, non-blocking I/O model.

2. The I/O (Input/Output) model refers not just to the input/output operations but also to anything ranging from writing/reading files on your local system to making an API request to read/write data to a remote system to routing the requests.

3. In the blocking I/O model, the subsequent code is blocked by the preceding code. Until an operation finishes its execution, the next operation cannot be performed.

4. In the non-blocking I/O model, the code is not blocked by the preceding code.

5. JavaScript follows the non-blocking I/O model.

The code that you looked at in the previous video is given below:

Code snippet:

/**
* OPERATION 1
* Function to get the user name from the server
*/
const getUserName = () => {
   let name = null;
   setTimeout(() => {
       name = 'Srishti';
       console.log(name);
   }, 2000);
}

/**
* OPERATION 2
* Function to get the past orders from the server
*/
const getPastOrders = () => {
   let orderDetails = null;
   setTimeout(() => {
       orderDetails = {
           orderId: '101',
           amount: 500,
           discount: 50
       }
       console.log(orderDetails);
   }, 2000);
}

getUserName();
getPastOrders();

Output:

Srishti
{ orderId: '101', amount: 500, discount: 50 }

The non-blocking I/O model is possible due to the JavaScript runtime. 

In the next video, you will look at an important point to be remembered with the non-blocking I/O model followed by JavaScript.