Computer Science Lectures

APP NOTES

Setting up the API Key
javascript

const apiKey = ‘4ff547d0e0204170c4b48ea3818faefa’;

// Replace with your actual API key
apiKey stores the API key needed to authenticate requests to the OpenWeatherMap API.

This string is used to access the weather data from the service for a given city.
jQuery Ready Function

\

$(document).ready(function () {
console.log(‘jQuery and script.js are working!’);

$(document).ready(…) waits until the HTML document is fully loaded before running the code inside it.
console.log(‘…’) prints a message to the console to confirm that the script and jQuery are working correctly.

Event Listener for the Search Button

$(‘#searchBtn’).click(function () {
const city = $(‘#cityInput’).val();

$(‘#searchBtn’).click(…) attaches a click event listener to an element with the ID searchBtn.
const city = $(‘#cityInput’).val(); retrieves the value entered in the input field with the ID cityInput and assigns it to the variable city.

if (city) {
getWeather(city); // Call the function with the city name
} else {
alert(‘Please enter a city name’);
}
});
});

if (city) checks if a city name has been entered. If it has:
getWeather(city); calls the getWeather function with city as an argument.
If no city name is entered, an alert message asks the user to enter one.

Function to Fetch Weather Data from the API

function getWeather(city) {
const apiUrl = https://api.openweathermap.org/data/2.5/weather?q=${city}&appid=${apiKey}&units=metric;

getWeather(city) is a function that takes city as a parameter.
const apiUrl = … constructs the full API URL, embedding the city name, apiKey, and setting units to metric (°C).

$.ajax({
url: apiUrl,
type: ‘GET’,
dataType: ‘json’,
success: function (data) {
displayWeather(data);
},
error: function () {
alert(‘City not found. Please try again.’);
}
});
}

$.ajax(…) sends a GET request to the API to fetch weather data for the specified city.
url: apiUrl specifies the API endpoint URL.
type: ‘GET’ indicates that it is a GET request.
dataType: ‘json’ expects the API response to be in JSON format.
success: function (data) {…} is executed if the request is successful.
displayWeather(data); calls the displayWeather function with the fetched data as an argument.
error: function () {…} is executed if the request fails, displaying an alert with an error message.

Function to Display the Weather Data

function displayWeather(data) {
const cityName = data.name;
const temperature = data.main.temp;
const feelsLike = data.main.feels_like;
const humidity = data.main.humidity;
const windSpeed = data.wind.speed;
const description = data.weather[0].description;
const icon = http://openweathermap.org/img/wn/${data.weather[0].icon}@2x.png;
displayWeather(data) is a function that takes the JSON data returned by the API and extracts key pieces of information.
const cityName = data.name; stores the city name.
const temperature = data.main.temp; retrieves the current temperature.
const feelsLike = data.main.feels_like; retrieves the “feels like” temperature.
const humidity = data.main.humidity; retrieves the humidity percentage.
const windSpeed = data.wind.speed; retrieves the wind speed in meters per second.
const description = data.weather[0].description; retrieves a description of the weather condition (e.g., “clear sky”).
const icon = … constructs a URL for the weather icon image associated with the current condition.

$(‘#weatherResult’).html

( <h2>${cityName}</h2>
<img src="${icon}" alt="Weather Icon">
<p>Temperature: ${temperature} °C</p>
<p>Feels Like: ${feelsLike} °C</p>
<p>Condition: ${description}</p>
<p>Humidity: ${humidity}%</p>
<p>Wind Speed: ${windSpeed} m/s</p> );
}

$(‘#weatherResult’).html(…) selects the HTML element with ID weatherResult and updates its contents using template literals (${…}) to insert the data.
h2 displays the city name.
img displays the weather icon.
p elements show the temperature, “feels like” temperature, weather condition, humidity, and wind speed.

Here’s a breakdown of all the symbols in the code, including keywords, operators, and punctuation, along with explanations of their roles in the code.

Variable Declaration Symbols
const

Declares a constant variable whose value cannot be changed later in the code.

Assignment operator that sets a variable equal to a specific value.
Strings and Template Literals
‘…’

Single quotes used to define a string value, such as ‘Please enter a city name’.
“…”

Double quotes are also used to define a string, usually seen in HTML within the html method and URL construction for image sources.
...${variable}...

Template literals (backticks) allow embedding variables directly within a string using ${}. It’s used to build URLs dynamically or insert values within strings.
jQuery Symbols
$

This is the main jQuery function. It’s used to select HTML elements or call jQuery methods, such as $(document).ready(…) and $.ajax(…).
(…)

Parentheses used to:
Enclose arguments for functions like $(…), .click(…), and .ready(…).
Group expressions or create conditions, such as if (city).
Invoke functions, like getWeather(city).
.

Dot operator is used to access properties or methods of an object.
For example, $(‘#cityInput’).val() gets the value of #cityInput, and data.main.temp accesses the temp property of the main object within data.
Functions and Conditional Statements
function

Keyword to define a function, such as function getWeather(city) {…}.
if (…)

Conditional statement that executes code within {} if the condition inside (…) is true.
else

Executes the code inside {} if the if condition is false.
Callback Functions and Events
=> (Arrow Function)

This shorthand syntax for functions isn’t actually in the code you provided, but the standard function (…) {…} syntax is used instead.
function (…) {…}

Function syntax with the function keyword, arguments in (…), and body enclosed in {…}.
Objects and JSON
{…}

Curly braces denote an object or block of code. For instance:
{ url: apiUrl, type: ‘GET’ … } defines an object for the $.ajax() method.
{…} also contains the body of functions and if statements.
:

Used to assign values to properties in an object. For instance, url: apiUrl assigns the apiUrl variable to the url property of the object.
Array Indexing
[0]
Array indexing operator, used to access elements within an array. For instance, data.weather[0].description retrieves the first element in the weather array.
Operators
+

Concatenation operator when used with strings, such as ‘‘. Adds together two values or combines strings.
!

Logical NOT operator used to negate a condition in JavaScript (not present in the code, but if we had if (!city), it would mean “if city is not present”).
API URL Construction
&

Used within URLs to join query parameters, as in &units=metric to specify units in the API request URL.
= (within URLs)

Specifies parameter values within a URL, like q=${city} in the apiUrl template literal, where q is the parameter and ${city} is its value.
HTTP Requests
GET
HTTP method specified within $.ajax to request data without modifying it.
jQuery Selectors
#
CSS selector symbol for selecting an element by its ID, like $(‘#searchBtn’).
End-of-Line and Block Symbols
;

Statement terminator in JavaScript. It ends a statement, such as const city = $(‘#cityInput’).val();.
//

Single-line comment symbol. Text following // on a line is ignored by the JavaScript interpreter.
jQuery HTML Injection
.html(…)
jQuery method that sets the HTML content of an element. For example, $(‘#weatherResult’).html(…) updates the content of the #weatherResult element with weather data.
Alert and Console Output
alert(…)

Displays a pop-up message to the user, as in alert(‘Please enter a city name’).
console.log(…)

Outputs a message to the console, which is useful for debugging.

CSS

Syntax

1. Selector – Defines which HTML elements to style.
2. Property – The aspect of the element being styled (e.g., color, margin).
3. Value – The setting for a property (e.g., red, 10px).
4. Rule-set – A combination of selectors and declarations.
5. Declaration – A property-value pair inside a rule-set.

Selectors

6. Class Selector – Selects elements with a specific class (e.g., .classname).
7. ID Selector – Targets an element with a specific ID (e.g., #idname).
8. Attribute Selector – Selects elements based on attributes (e.g., [type=”text”]).
9. Pseudo-class – Styles elements in a specific state (e.g., :hover).
10. Pseudo-element – Styles a specific part of an element (e.g., ::before).

Colors

11. Hex Code – A six-digit representation of color (e.g., #FFFFFF).
12. RGBA – Defines colors using red, green, blue, and alpha (transparency) (e.g., rgba(255, 255, 255, 0.5)).
13. HSL – Represents colors in hue, saturation, and lightness (e.g., hsl(120, 100%, 50%)).
14. Color Keywords – Named colors (e.g., red, blue, green).
15. Opacity – Defines the transparency of an element.

Backgrounds

16. Background-color – Sets the background color of an element.
17. Background-image – Applies an image as the background.
18. Background-size – Specifies the size of the background image.
19. Background-repeat – Determines if a background image repeats (e.g., no-repeat).
20. Background-position – Sets the starting position of a background image.

Borders

21. Border – A shorthand property for setting border width, style, and color.
22. Border-radius – Rounds the corners of an element’s border.
23. Border-collapse – Defines the behavior of table borders.
24. Border-style – Specifies the style of borders (e.g., solid, dashed).
25. Border-width – Sets the width of borders.

Margins and Padding

26. Margin – The space outside an element’s border.
27. Padding – The space inside an element’s border.
28. Margin-collapse – A behavior where adjacent vertical margins combine.
29. Box model – The concept of how width, height, padding, borders, and margins interact.
30. Margin auto – A value that centers an element horizontally.

Height/Width

31. Width – Specifies the width of an element.
32. Height – Specifies the height of an element.
33. Max-width – Sets the maximum width an element can take.
34. Min-width – Sets the minimum width an element can take.
35. Aspect ratio – Defines the proportional relationship between width and height.

Outline

36. Outline – A line that is drawn around elements, outside the border.
37. Outline-style – Specifies the style of the outline (e.g., solid).
38. Outline-color – Sets the color of the outline.
39. Outline-width – Defines the width of the outline.
40. Outline-offset – Space between the outline and the edge of an element.

Text

41. Text-align – Specifies the horizontal alignment of text (e.g., left, right, center).
42. Text-decoration – Sets text decorations (e.g., underline, line-through).
43. Text-transform – Controls the capitalization of text (e.g., uppercase).
44. Line-height – Sets the distance between lines of text.
45. Letter-spacing – Controls the spacing between characters.

Fonts

46. Font-family – Specifies the font for an element.
47. Font-size – Sets the size of the text.
48. Font-weight – Defines the thickness of the text (e.g., bold).
49. Font-style – Specifies the style of the font (e.g., italic).
50. Font-variant – Controls the usage of small caps.

Icons, Links, Lists, and Tables

51. List-style – Specifies the type of list item marker.
52. Table-layout – Defines the algorithm for table layout (e.g., fixed).
53. Text-indent – Indents the first line of text in an element.
54. Cursor – Specifies the type of cursor to be displayed (e.g., pointer).
55. Display – Defines how an element is displayed (e.g., block, inline).

Here are 10 more challenging CSS terms:

1. Margin-collapse – The behavior where adjacent vertical margins combine, affecting the spacing between elements in ways that can be counterintuitive.
2. Box model – A fundamental concept that describes how the width, height, padding, borders, and margins of an element interact and contribute to its layout.
3. Outline-offset – A property that defines the space between the outline and the border edge of an element, often used for visual effects.
4. Aspect ratio – A property that maintains the ratio of width to height of an element, particularly useful for responsive design.
5. Font-variant – A property that enables the use of small caps or other variant styles in typography, adding sophistication to text rendering.
6. Border-collapse – A property specifically for table elements that determines whether the borders are collapsed into a single border or separated.
7. Max-width and Min-width – Properties that control the maximum and minimum dimensions of an element, crucial for responsive design but can lead to unexpected layouts.
8. Text-indent – A property that allows for indentation of the first line of a text block, which can be tricky to implement in various contexts.
9. Background-size – A property that adjusts the size of a background image, which can affect how images are displayed across different screen sizes.
10. Line-height – While commonly used, the intricacies of how it interacts with different font sizes and the vertical rhythm of text can be complex and subtle.

/* This is a comment in CSS */

/* Styling the body element /

body

{ background-color: #f0f0f0; / Sets the background color of the page /

font-family: Arial, sans-serif; / Changes the font of the text /

color: #333; / Sets the text color /

margin: 0; / Removes default margin around the body /

padding: 20px; / Adds space inside the body */
}

/* Styling headings /

h1

{ font-size: 2.5em; / Makes the font size larger /

text-align: center; / Centers the heading /

color: #0056b3; / Changes the heading color */
}

/* Styling paragraphs /

p {

line-height: 1.6; / Increases space between lines for readability /

margin-bottom: 15px; / Adds space below each paragraph */
}

/* Styling links /

a

{ color: #007bff; / Sets the link color /

text-decoration: none; / Removes the underline from links */
}

a:hover {
text-decoration: underline; /* Underlines the link when hovered over */
}

/* Styling a button /

button

{ background-color: #28a745; / Sets the background color of the button /

color: white; / Changes the text color of the button /

border: none; / Removes the border /

padding: 10px 20px; / Adds space inside the button /

cursor: pointer; / Changes the cursor to a pointer on hover */
}

button:hover {
background-color: #218838; /* Darkens the button color on hover */
}

HTML

<h1> to <h6>: These are heading tags in HTML. <h1> represents the highest level heading, typically used for the main title, while <h6> is the lowest level heading. They help structure content hierarchically and improve accessibility and SEO.

style: An attribute used in HTML elements to apply CSS (Cascading Style Sheets) styles directly to that element. For example, <div style="color: red;"> changes the text color to red.

<p>: The paragraph tag, used to define a block of text. It automatically adds space before and after the paragraph, improving readability.

<!-- Comment -->: This syntax is used to insert comments in HTML code. Comments are not displayed in the browser and are used for code documentation.

<a>: The anchor tag, used to create hyperlinks. It can link to another web page, an email address, or an anchor within the same page.

<img>: The image tag, used to embed images in a webpage. It requires the src attribute to specify the image source.

background-color: A CSS property that sets the background color of an element. For example, background-color: blue; changes the background color to blue.

<ul>: The unordered list tag, used to create a list of items where the order does not matter. Items are typically marked with bullet points.

<table>: The table tag, used to create a table in HTML. It organizes data into rows and columns, making it easier to read.

href: An attribute of the <a> tag that specifies the URL of the page the link goes to. For example, href="https://example.com".

<ol>: The ordered list tag, used for creating a list of items where the order is significant. Items are typically numbered.

<div>: A division tag, used as a container for other HTML elements. It helps in structuring the webpage and applying styles.

alt: An attribute of the <img> tag that provides alternative text for the image. It is important for accessibility and is displayed if the image fails to load.

border: A CSS property used to specify the border around elements. For example, border: 1px solid black; creates a solid black border.

text-align: A CSS property that sets the horizontal alignment of text within an element. Possible values include left, right, center, and justify.

font-size: A CSS property that specifies the size of the font used in text. For example, font-size: 16px; sets the font size to 16 pixels.

color: A CSS property that sets the color of the text within an element. For example, color: red; changes the text color to red.

<span>: An inline container used to apply styles or JavaScript to a portion of text without breaking the flow of content.

<li>: The list item tag, used within <ul> or <ol> to define individual items in a list.

<tr>: The table row tag, used to define a row of cells in a table, typically containing <td> (table data) or <th> (table header) elements.

12’s

<abbr>: The abbreviation tag, used to represent an abbreviation or acronym. It can include a title attribute for the full form.

<bdi>: The bidirectional isolation tag, used to isolate a part of text that may have a different directionality (like mixed languages) from surrounding text.

<bdo>: The bidirectional override tag, which allows you to change the text direction of its contents, overriding the default direction.

<canvas>: A tag used for drawing graphics via scripting (usually JavaScript). It creates a blank rectangular area on the page.

<details>: A tag that creates a disclosure widget from which the user can obtain additional information or controls. It can be opened or closed by the user.

<dialog>: A tag for creating dialog boxes or pop-up windows, which can be opened and closed programmatically.

<mark>: The mark tag, used to highlight text that is of special interest or relevance, typically displayed with a yellow background.

<progress>: A tag that represents the completion progress of a task, such as file uploads, typically displayed as a progress bar.

<summary>: Used in conjunction with <details>, it defines a summary or heading for the details that can be expanded or collapsed.

<time>: A tag that represents a specific time or date, often with a datetime attribute to provide a machine-readable format.

<template>: A tag that holds client-side content that is not rendered when the page loads but can be instantiated later via JavaScript.

<wbr>: The word break opportunity tag, which suggests a line break opportunity within a word, useful for long words in narrow containers.

<base>: A tag that specifies a base URL for all relative URLs in a document. It typically appears in the <head> section.

<link>: A tag used to link to external resources, such as stylesheets, icons, or preconnect hints, generally found in the <head> section.

<meta>: A tag used to provide metadata about the HTML document, such as character set, author, viewport settings, and more.

<noscript>: A tag that defines content to be displayed when scripts are not supported or are disabled in the user’s browser.

<picture>: A tag that provides a way to specify multiple image sources for responsive design, allowing different images to load based on conditions like screen size.

<source>: A tag used within <audio> and <video> elements to specify multiple media resources for playback.

<track>: A tag used to specify text tracks for <video> and <audio> elements, providing captions, subtitles, or descriptions.

<iframe>: An inline frame tag that allows you to embed another HTML document within the current document.

<embed>: A tag used to embed external content, such as multimedia (audio or video) or interactive applications.

<object>: A tag used to embed multimedia, such as images, audio, or video, or other external resources like PDFs.

<param>: A tag used within <object> to define parameters for the object being embedded, such as settings for plugins.

<keygen>: A tag that was used to generate key pairs for secure client-side cryptography. It is now deprecated in HTML5.

<canvas>: Used to create graphics on the fly via JavaScript. It can be used for drawing shapes, text, images, and more.

<script>: A tag used to include JavaScript code or to link to an external JavaScript file.

<script type="module">: A type attribute that specifies that the JavaScript should be treated as a module, allowing the use of import and export.

<meta charset>: A specific <meta> tag that sets the character encoding for the HTML document, essential for correctly displaying characters.

<fieldset>: A tag used to group related elements in a form, often with a <legend> for a caption.

<legend>: A tag used within <fieldset> to provide a title or explanation for the group of related elements.

AI

1. Definition: AI is the simulation of human intelligence in machines, enabling them to perform tasks that usually require human intelligence.
2. Types: AI can be narrow (focused on one task) or general (able to learn and do many things).
3. Applications: AI is used in voice assistants, recommendation systems, and self-driving cars.
   

Machine Learning (ML)

1. Definition: ML is a type of AI where machines learn from data instead of being explicitly programmed.
2. Types: Supervised (with labeled data), unsupervised (without labeled data), and reinforcement learning (learning by trial and error).
3. Real-World Uses: Spam filters, movie recommendations, and facial recognition.
   

Narrow AI

1. Definition: Narrow AI is specialized for one task, like playing chess or recognizing faces.
2. Focus: It cannot perform tasks outside its training area.
3. Examples: Siri, Alexa, Google Maps.
   

Neural Networks

1. Definition: Neural networks are algorithms inspired by the human brain that learn from data.
2. Structure: They consist of layers of interconnected nodes (neurons) that process data in steps.
3. Uses: Image recognition, speech processing, and language translation.
   

Perceptrons

1. Definition: A perceptron is the simplest type of neural network, used in binary classification tasks.
2. Function: It takes inputs, applies weights, and uses an activation function to make decisions.
3. Limitations: It can only solve simple problems, like distinguishing between two categories.
   

Deep Neural Networks (DNNs)

1. Definition: DNNs are large neural networks with many layers of nodes, making them powerful for complex tasks.
2. Capabilities: They can detect patterns in images, sounds, and text.
3. Training: Requires large datasets and powerful computers.
   

Deep Learning

1. Definition: Deep learning is a subset of ML using DNNs to model complex patterns in data.
2. Applications: Self-driving cars, speech recognition, and medical diagnosis.
3. Challenges: Requires a lot of data and processing power.
   

Strong AI

1. Definition: Strong AI is a theoretical type of AI that can perform any intellectual task that a human can do.
2. Goal: Create machines with human-like consciousness and reasoning.
3. Current Status: We have not yet achieved strong AI.
   

ML Languages

1. Popular Languages: Python, R, Java, and JavaScript are common languages for ML.
2. Why Python?: It has many libraries and is easy to learn for beginners.
3. JavaScript: Useful for ML models on the web, especially with libraries like TensorFlow.js.
   

ML in JavaScript

1. In-Browser ML: JavaScript can run ML models directly in the browser using libraries like TensorFlow.js or Brain.js.
2. Accessibility: It allows ML to be used in websites and web applications without a server.
3. Limitations: Slower than Python for large-scale ML tasks.
   

ML Libraries

1. TensorFlow: A popular ML library by Google for building models in Python and JavaScript.
2. Scikit-learn: A Python library for simple ML tasks like classification and regression.
3. PyTorch: An advanced library for deep learning, used for research and production.
   

Clustering

1. Definition: Clustering is an unsupervised learning technique where similar data points are grouped together.
2. Examples: Grouping customers by buying habits or segmenting images by colors.
3. Algorithms: K-means and hierarchical clustering are popular methods.
   

TensorFlow

1. Definition: TensorFlow is a powerful ML framework for building and training models.
2. Flexibility: It supports everything from small experiments to large production systems.
3. Languages: It can be used with Python, JavaScript (TensorFlow.js), and others.
   

Brain.js

1. Definition: Brain.js is a JavaScript library for neural networks that runs in browsers or Node.js.
2. Use Cases: Great for small-scale AI applications like pattern recognition or predictions.
3. Simplicity: Ideal for introducing ML concepts to beginners using JavaScript.
   

Data Sets

1. Definition: A data set is a collection of data used to train and test machine learning models.
2. Types: Can be labeled (for supervised learning) or unlabeled (for unsupervised learning).
3. Examples: Text, images, or sensor data.
   

Mean, Median, Mode

1. Mean: The average value of a dataset.
2. Median: The middle value when data is arranged in order.
3. Mode: The most frequent value in the dataset.
   

Standard Deviation

1. Definition: A measure of how spread out the data is from the mean.
2. Low vs High: A low standard deviation means data points are close to the mean, and high means they are spread out.
3. Use: Helps assess the consistency of a dataset.
   

Percentiles

1. Definition: Percentiles divide data into 100 equal parts.
2. Common Percentiles: The 25th percentile is the first quartile, and the 75th percentile is the third quartile.
3. Use: Percentiles are useful for comparing data, like test scores in a population.
   

Decision Tree

1. Definition: A decision tree is an ML model that makes decisions by splitting data into branches.
2. Structure: It has nodes (decisions) and leaves (outcomes).
3. Uses: Decision trees are used in classification and regression problems.

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ChatGPT

1. Definition: A large language model trained to understand and generate text based on user input.
2. Use Cases: Writing, answering questions, and generating content.
3. Limitations: It cannot understand context like a human and may produce incorrect answers.
   

Prompt Writing

1. Definition: Writing clear and specific instructions for an AI like ChatGPT to get useful responses.
2. Best Practices: Be clear, concise, and provide relevant context.
3. Examples: “Write an essay about climate change” or “Explain quantum physics simply.”
   

Role Prompting

1. Definition: Assigning a role to an AI in a prompt to shape its response.
2. Examples: “Act as a teacher explaining programming” or “Be a customer service agent helping with a return.”
3. Benefit: Helps guide the AI to provide more context-specific answers.

AI – 11 things they’ never told you’re not telling you about AI

I-Robot Clips

Machine Learning and AI

Neural Networks

Perceptrons

Deep Learning

Narrow vs Strong AI

AI Languages – JS, Pythons, C++, R, Lisp

TenserFlow

HTML

CSS

JS