HTTP requests are an essential part of web development, as they allow you to send and receive data from remote servers. In JavaScript, there are two main ways to make HTTP requests: using the XMLHttpRequest object, or using the newer fetch API. In this article, we’ll take a look at both approaches and see how to use them to make HTTP requests in your JavaScript code.
What Is Http?
HTTP stands for Hypertext Transfer Protocol. It is a protocol for sending and receiving data over the internet. When you enter a URL into your web browser and hit Enter, your browser sends an HTTP request to the server that hosts the website. The server then sends an HTTP response back to your browser, which includes the data for the webpage (usually in the form of HTML, CSS, and JavaScript).
HTTP is a stateless protocol, which means that the server does not retain any information about the client between requests. This makes it easy to scale, but it also means that it is not well-suited for applications that require long-running connections or real-time communication.
There are several different HTTP methods that can be used in a request, including GET, POST, PUT, DELETE, and others. The method indicates the type of action that the request is intended to perform. For example, a GET request is used to retrieve data from the server, while a POST request is used to send data to the server (such as when submitting a form).
HTTP is an important foundation of the web, and is used by almost all websites and web-based applications.
What is JavaScript?
JavaScript is a programming language that is commonly used to add interactivity to web pages. It is a client-side language, which means that it runs in the user’s web browser, rather than on a server.
JavaScript is an object-oriented language, which means that it is based on the concept of objects and their interactions. It is also a dynamically-typed language, which means that you don’t have to specify the data type of a variable when you declare it.
JavaScript is most often used in conjunction with HTML and CSS to create web applications. It allows you to manipulate the content and layout of a web page, and to create interactive elements such as drop-down menus and forms.
JavaScript is also used in a variety of other contexts, such as in mobile app development, game development, and server-side programming with technologies like Node.js.
Section 1: XMLHttpRequest
The XMLHttpRequest object is a built-in browser object that allows you to make HTTP requests from JavaScript. It has been around since the early days of the web, and is still widely used today.
To make an HTTP request with XMLHttpRequest, you first need to create a new instance of the object:
Next, you need to specify the HTTP method and URL that you want to send the request to. You can do this using the open method:
The first argument is the HTTP method (e.g. GET, POST, PUT, DELETE), and the second argument is the URL.
Once you have set up the request, you can send it using the send
method:
You can also pass a payload to the send
method if you are making a POST, PUT, or DELETE request. For example, to send a JSON payload in the body of a POST request, you would do something like this:
To handle the response from the server, you can set an event handler for the onreadystatechange
event. This event is fired every time the readyState
property of the XMLHttpRequest
object changes. When the request is complete, the readyState
will be set to DONE
, and the responseText
property will contain the response from the server.
Here’s an example of how to handle the response using the onreadystatechange
event:
Section 2: fetch
The fetch
API is a newer way to make HTTP requests in JavaScript, and is built into modern browsers. It uses promises, which makes it easier to work with than XMLHttpRequest
.
To make an HTTP request with fetch
, you simply call the fetch
function and pass it the URL that you want to send the request to:
The fetch
function returns a promise that resolves with a Response
object.
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