Unit 2: jQueryLesson 1: Introduction to jQuery

October 2, 2013

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Recap of Unit 1 (I)

• HTML is very important and is used in everything from websites to email messages to sending data with forms

• HTML files are easy to create – no harder than writing a Word document

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Recap of Unit 1 (II)

• Using HTML, we can add images, video, and forms to create a rich experience for the visitors to our website

• Meta tags and search engine optimization help potential visitors to find our website on search engines like Google or Yahoo

This is the meta description tag

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Recap of Unit 1 (III)

• CSS is just as important as HTML because it allows us to style a page to make it look pretty

• CSS always needs to be paired with HTML for the styling to take effect, but due to separation of concerns, they should be split into two separate files

HTML HTML

CSS

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Recap of Unit 1 (IV)

• Remember the DRY Principle: Don’t Repeat Yourself. Reuse code whenever possible!

• Using open source code and frameworks like Twitter Bootstrap can save us a lot of time

Unit 2 will focus on jQuery

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Unit 1:HTML/CSS

Unit 2:jQuery

Unit 3:Javascript

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Lesson 1: Introduction to jQuery

Introduction to jQuery

Syntax and Structure Abstraction

Pictures, Video, and

Media

HTML and Forms

Search Engine

Optimization

Learning to Use CSS

Introduction to CSS

Reusing Code

3 Ways to Use CSS

Separation of Concerns

Launching Your Own Website

Lesson 1 Lesson 2 Lesson 3 Lesson 4

Lesson 8 Lesson 7 Lesson 6 Lesson 5

Lesson 9 Lesson 10 Lesson 11 Lesson 12

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HTML/CSS alone have limited capabilities

• We’ve seen that HTML and CSS are excellent tools for creating webpages, but they don’t allow us to do everything we might want

• Remember our Prince William analogy from Unit 1?

HTML as the structure/skeleton

CSS as the presentation/clothing

jQuery/Javascript as the action/movement

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jQuery gives us the ability to animate a website

• To animate our webpage, we need to learn a new language – jQuery

• We’re learning jQuery for two main purposes:

1. Make dynamic websites that engage and interact with our users

2. Take advantage of the full range of our computer’s power

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jQuery appears everywhere on the web

• jQuery is now used by more than half of the top 10,000 websites

• You’ve probably visited many of these, such as Amazon, The Guardian, and ESPN

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So what exactly is jQuery?

• jQuery is one of the fastest ways to bring movement to a webpage and have it come to life!

• It’s easy to use because it’s not a programming language of its own; instead it is a library (a bunch of commonly used pieces of code), written in a programming language called Javascript

• To use jQuery, you don’t need to know Javascript (we will cover this in detail in Unit 3)

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Think of jQuery as a phrase book (I)

• If you’re getting ready to visit France, but don’t speak any French, you could buy a French phrase book – a book that has translations for commonly used phrases:

• While we may not understand the individual words (what does qu’il or quelqu’un mean by themselves?), we can still use the entire phrase to convey what we mean

Is there someone here who speaks English?

Est-ce qu’il y a quelqu’un ici qui parle anglais?

English French

Do you speak English? Parlez-vous anglais?

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Think of jQuery as a phrase book (II)

• Just as a French phrase book helps us understand common phrases without knowing individual words, jQuery helps us with common features without needing to understand Javascript

• Some of the common features we might want to enable include:

• Zoom in on an image

• Slowly fade in some text

• Slide down a box when clicked

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Think of jQuery as a phrase book (III)

• jQuery takes the Javascript code needed to run each of these common features and packages them into some simple commands

• For example, the complicated Javascript code on the left becomes the much simpler jQuery on the right

jQueryJavascript

$(document).ready(function() { $('a').click(function() { alert('hello'); });});

var anchors =document.getElementsByTagName(“a”);for(var z =0; z < anchors.length; z++){ var elem = anchors[z]; elem.onclick = function(){ alert(“hello”); };}

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jQuery can transform a static webpage into a dynamic, interactive website

Before After

Date inputted using a regular HTML form

Date inputted through a jQuery calendar popup

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Examples of jQuery in action (I)

“Password Meter” evaluates password strength

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Examples of jQuery in action (II)

Numbers and circular bars update in real-time

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Examples of jQuery in action (III)

Image appears when cursor hovers over tooltip

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Summary (I)

• jQuery is one of the fastest ways to bring movement to a webpage and have it come to life

• It’s easy to use because it’s not a programming language of its own; instead it is a library (a bunch of commonly used pieces of code), written in a programming language called Javascript

• To use jQuery, you don’t need to know Javascript (we will cover this in detail in Unit 3)

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Summary (II)

• Just as a French phrase book helps us understand common phrases without knowing individual words, jQuery helps us with common features without needing to understand Javascript

• jQuery takes the Javascript code needed to run each of these common features and packages them into some simple commands

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What to do on your own

1. Go to URL to complete the Codecademy course online

2. Do the practice set on the material learned

3. Take the follow-up quiz to test your understanding