How to use curl in JavaScript?

Are you tired of looking for solutions on how to use curl in JavaScript?

Worry no more because in this article, you’ll learn about curl, a powerful command-line tool for transferring data with URLs.

Discover its use in Linux and PHP for making HTTP requests and explore alternatives in JavaScript, like using XMLHttpRequest, fetch function, or libraries like axios.

What is curl in JavaScript?

Curl is a command line tool and library for transferring data with URLs. It supports a wide range of protocols, including HTTP, HTTPS, FTP, and many others.

Developers use curl to send and receive data from a server by specifying the server’s location (in the form of a URL) and the data they want to send or receive.

Curl is widely used for testing APIs, downloading files, and automating data transfer processes.

You must know that curl commonly used in Linux and PHP to make HTTP requests.

However, curl does not exist in JavaScript. Instead, you can use XMLHttpRequest or the fetch function to make HTTP requests from JavaScript.

For example, you can use the fetch function to make a GET request to a URL like this:

(async () => {
const res = await fetch('https://yesno.wtf/api')
const answer = await res.json()
console.log(answer)
})()

You can also use libraries such as jQuery to send AJAX requests

What does HTTP GET request means?

The HTTP GET request method is used to retrieve data from a server. It is one of the most common HTTP methods and is used to request a representation of a specified resource.

GET requests should only be used to retrieve data and should not include data. If you want to send data to the server, you should use other HTTP methods such as POST, PUT, or DELETE.

How to use curl?

To use curl, you’ll need to open a command line interface (CLI) such as the terminal on macOS or Linux, or the command prompt on Windows.

Once you have the CLI open, you can start using curl by typing the curl command followed by the options and the URL you want to interact with.

For instance, if you want to retrieve data from a website using the GET method, you can type

curl http://www.sample.com ✅

This will send a GET request to the specified website and return the HTML source code for that page.

You can also use curl to send data to a server using the POST method. For example, if you want to send data in JSON format to an API endpoint, you can type:

 curl --data '{"key1":"value1", "key2":"value2"}' http://www.sample.com/api ✅

This will send a POST request to the specified API endpoint with the data you provided in JSON format.

Curl has many other options and features that you can use. You can learn more about them by reading the Curl documentation or by typing the following in your CLI:

curl --help or man curl  ✅

How to create a curl request in JavaScript?

As we mentioned earlier, curl is a command-line tool and library for transferring data with URLs. It is commonly used in Linux and PHP to make HTTP requests.

However, curl does not exist in JavaScript. Instead, you can use XMLHttpRequest or the fetch function to make HTTP requests from JavaScript.

Here’s an example of how you can use the fetch function to make a POST request to a URL with some data:

(async () => {
const res = await fetch('https://jsonplaceholder.typicode.com/posts', {
method: 'POST',
body: JSON.stringify({
title: 'foo',
body: 'bar',
userId: 1
}),
headers: {
'Content-type': 'application/json; charset=UTF-8'
}
})
const answer = await res.json()
console.log(answer)
})()

This code uses the fetch function to make a POST request to the specified URL with some data. The data is sent as a JSON string in the request body. The response is then parsed as JSON and logged to the console.

Alternative way to create a curl request in JavaScript

You can use the XMLHttpRequest object or the more modern fetch() function to make HTTP requests similar to curl.

Use fetch function

Here’s an example of how to make a GET request to an API endpoint using fetch():

fetch('https://api.sample.com/data')
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error(error))

This code sends a GET request to the specified API endpoint and logs the returned data to the console.

You can also use fetch() to make other types of HTTP requests, such as POST, PUT, and DELETE, by specifying the request method and any necessary data in the options object.

Here’s an example of how to make a POST request with JSON data using fetch():

fetch('https://api.example.com/data', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify({
key1: 'value1',
key2: 'value2'
})
})
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error(error))

This code sends a POST request with JSON data to the specified API endpoint and logs the returned data to the console.

Use XMLHttpRequest

Here’s the examples of how you can use the XMLHttpRequest object to make HTTP requests similar to curl:

const xhr = new XMLHttpRequest()
xhr.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
console.log(this.responseText)
}
}
xhr.open('GET', 'https://yesno.wtf/api', true)
xhr.send()

This code creates a new XMLHttpRequest object, sets an event listener for the readystatechange event, opens a connection to the specified URL using the GET method, and sends the request.

When the response is received, the event listener logs the response text to the console.

Use axios library

In addition to using the fetch function or the XMLHttpRequest object, you can also use third-party libraries such as axios or request to make HTTP requests from JavaScript.

Here’s an example of how you can use the axios library to make a POST request to a URL with some data:

const axios = require('axios')

async function makeRequest() {
const res = await axios.post('https://jsonplaceholder.typicode.com/posts', {
title: 'foo',
body: 'bar',
userId: 1
})
console.log(res.data)
}

makeRequest()

This code uses the axios.post method to make a POST request to the specified URL with some data. The data is sent as a JSON object in the request body. The response is then logged to the console.

How to install curl?

To install curl on your computer, you need to follow different steps depending on your operating system.

For Windows

You can download the installer package or the zip file from the curl website or use a package manager like vcpkg.

After downloading, you need to install recent CA certificates and copy them to the same folder where you placed curl.exe.

You can set the curl path in the environment variables or invoke it from a command window. You can choose the 64-bit or 32-bit version depending on your operating system .

For macOS

You can use the Homebrew package manager to install curl by running the command brew install curl in the terminal.

For Linux

You can use your system’s package manager to install curl .

For example, on Ubuntu or Debian-based systems, you can run the command sudo apt-get install curl in the terminal.

Conclusion

In conclusion, this article explores curl in JavaScript, a command line tool and library for transferring data with URLs.