PROGRAMMING FOR THE WEB: THE INTERNET
DEV TOOLS

Introduction to Developer Tools

Web browsers play a crucial role in web development, not just for displaying web pages but also for providing powerful tools that aid developers in creating, debugging, and optimizing web applications. One of the most important features modern browsers offer is the set of Developer Tools, often referred to as DevTools.

What are Developer Tools?

Developer Tools are built-in features in modern web browsers that allow web developers to inspect, debug, and optimize websites and web applications. They provide a wide range of functionalities, including:

DOM Inspection: Allows developers to view and manipulate the Document Object Model (DOM) of a web page in real-time.
CSS Editing: Enables on-the-fly viewing and modification of CSS styles applied to elements.
JavaScript Debugging: Provides tools for setting breakpoints, stepping through code, and inspecting variables.
Network Analysis: Allows monitoring of network requests and responses, crucial for understanding HTTP interactions.
Performance Profiling: Helps identify performance bottlenecks in web applications.
Console: Provides a command-line interface for JavaScript execution and logging.
Responsive Design Testing: Allows testing of web pages across various screen sizes and devices.

Importance of Developer Tools in Web Development

Debugging: DevTools make it easier to identify and fix issues in HTML, CSS, and JavaScript code.
Performance Optimization: They help in analyzing load times, rendering performance, and resource usage.
Cross-browser Compatibility: Developers can test how their sites behave across different browsers and devices.
Learning and Exploration: For students, DevTools provide a way to explore how websites are built and how web technologies interact.
Prototyping: Quick changes can be made and previewed without modifying the source code.
Security Analysis: Some DevTools features help in identifying potential security issues.

Exploring HTTP with Chrome DevTools

Objective

To gain experience with HTTP concepts using Google Chrome's Developer Tools.

Instructions

Part 1: Accessing Developer Tools

Open Google Chrome.
Press F12 on your keyboard.
In the Developer Tools window, click on the "Network" tab.

Questions:

Part 2: Observing HTTP Requests and Responses

Clear the network log by clicking the "Clear" button in the Network tab.
Navigate to https://httpbin.org/get in your browser.
Observe the requests that appear in the Network tab.
Click on the request with the name "get".

a) What is the HTTP method used for this request?

b) What is the status code of the response?

c) Can you find the "User-Agent" header in the request headers? What information does it provide?

Part 3: Exploring Query Parameters

Clear the network log again.
Navigate to https://httpbin.org/get?name=Student&class=SoftwareEngineering
Click on the "get" request in the Network tab.

d) Look at the "Query String Parameters" section. What parameters do you see?

e) How are these parameters represented in the URL?

Part 4: Examining POST Requests and Request Bodies

Clear the network log.
Navigate to https://httpbin.org/forms/post
Fill in the form with some test data and submit it.
Find the POST request in the Network tab and click on it.

f) What is the HTTP method used for this request?

g) Look at the "Request Payload" or "Form Data" section. Can you see the data you submitted?

h) What is the "Content-Type" header for this request?

Part 5: Analyzing Status Codes

Clear the network log.
Navigate to the following URLs and observe the status codes:

i) What do each of these status codes mean?

j) How might these status codes be useful when debugging a web application?

Part 6: Exploring Cookies

Clear the network log.
Navigate to https://httpbin.org/cookies/set?name=John%20Smith&status=guest
Now go to https://httpbin.org/get
Find the "Cookies" section in the Network tab and click on it.

k) What two cookies have been set for this website?

l) Can you find where in the dev tools to modify cookies? Are you able to set your status to "admin"?

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