Authentication & Databases

In this focused lecture, Harkirat covers crucial async concepts—Fetch, callbacks, promises, and async/await—as well as delves into Authentication strategies and Databases, specifically the MongoDB database.

fetch() Method

The fetch() method in JavaScript is a modern API that allows you to make network requests, typically to retrieve data from a server. It is commonly used to interact with web APIs and fetch data asynchronously. Here's a breakdown of what the fetch() method is and why it's used:

What is the fetch() Method?

The fetch() method is a built-in JavaScript function that simplifies making HTTP requests. It returns a Promise that resolves to the Response to that request, whether it is successful or not.

Why is it Used?

1. Asynchronous Data Retrieval:
   • The primary use of the fetch() method is to asynchronously retrieve data from a server. Asynchronous means that the code doesn't wait for the data to arrive before moving on. This is crucial for creating responsive and dynamic web applications.
2. Web API Interaction:
   • Many web applications interact with external services or APIs to fetch data. The fetch() method simplifies the process of making HTTP requests to these APIs.
3. Promise-Based:
   • The fetch() method returns a Promise, making it easy to work with asynchronous operations using the .then() and .catch() methods. This promotes cleaner and more readable code.
4. Flexible and Powerful:
   • fetch() is more flexible and powerful compared to older methods like XMLHttpRequest. It supports a wide range of options, including headers, request methods, and handling different types of responses (JSON, text, etc.).

Basic Example:

Here's a basic example of using the fetch() method to retrieve data from a server:

fetch('<https://api.example.com/data>')
  .then(response => {
    if (!response.ok) {
      throw new Error(`HTTP error! Status: ${response.status}`);
    }
    return response.json();
  })
  .then(data => {
    console.log('Data from server:', data);
  })
  .catch(error => {
    console.error('Fetch error:', error);
  });

In this example, we use fetch() to make a GET request to 'https://api.example.com/data', handle the response, and then parse the JSON data. The .then() and .catch() methods allow us to handle the asynchronous flow and potential errors.