Parsing HTTP Cookies in JavaScript

Introduction

In this lab, we will dive into the topic of parsing HTTP cookies in JavaScript. The purpose of this lab is to provide a hands-on experience of how to extract and organize cookie data from an HTTP header string. By the end of this lab, you will have a clear understanding of how to use the parseCookie function to create an object containing all cookie name-value pairs.

JavaScript Function to Parse HTTP Cookies

To parse an HTTP Cookie header string in JavaScript and return an object of all cookie name-value pairs, follow these steps:

• Open the Terminal/SSH and type node to start practicing coding.
• Use String.prototype.split() to separate key-value pairs from each other.
• Use Array.prototype.map() and String.prototype.split() to separate keys from values in each pair.
• Use Array.prototype.reduce() and decodeURIComponent() to create an object with all key-value pairs.

Here's an example of the parseCookie() function that implements the above steps:

const parseCookie = (str) =>
  str
    .split(";")
    .map((v) => v.split("="))
    .reduce((acc, v) => {
      acc[decodeURIComponent(v[0].trim())] = decodeURIComponent(v[1].trim());
      return acc;
    }, {});

You can test the function as follows:

parseCookie("foo=bar; equation=E%3Dmc%5E2");
// { foo: 'bar', equation: 'E=mc^2' }

Summary

Congratulations! You have completed the Parse Cookie lab. You can practice more labs in LabEx to improve your skills.