JavascriptCOmpleteGuideCourseFromZero.pptx

Instructor : Alaeddine Theljani Intro to Javascript 1

Client Side Scripting 2

Why use client-side programming? PHP already allows us to create dynamic web pages. Why also use client-side scripting? client-side scripting (JavaScript) benefits: usability : can modify a page without having to post back to the server (faster UI) efficiency : can make small, quick changes to page without waiting for server event-driven : can respond to user actions like clicks and key presses 3

Why use client-side programming? server-side programming (PHP) benefits: security : has access to server's private data; client can't see source code compatibility : not subject to browser compatibility issues power : can write files, open connections to servers, connect to databases, ... 4

What is Javascript ? a lightweight programming language ("scripting language") used to make web pages interactive insert dynamic text into HTML (ex: user name) react to events (ex: page load user click) get information about a user's computer (ex: browser type) perform calculations on user's computer (ex: form validation) 5

What is Javascript ? a web standard (but not supported identically by all browsers) NOT related to Java other than by name and some syntactic similarities 6

Javascript vs Java interpreted, not compiled more relaxed syntax and rules fewer and "looser" data types variables don't need to be declared errors often silent (few exceptions) key construct is the function rather than the class "first-class" functions are used in many situations contained within a web page and integrates with its HTML/CSS content 7

Javascript vs Java 8 + =

JavaScript vs. PHP similarities: both are interpreted, not compiled both are relaxed about syntax, rules, and types both are case-sensitive both have built-in regular expressions for powerful text processing 9

JavaScript vs. PHP differences: JS is more object-oriented: noun.verb (), less procedural: verb(noun) JS focuses on user interfaces and interacting with a document; PHP is geared toward HTML output and file/form processing JS code runs on the client's browser; PHP code runs on the web server 10 JS <3

Linking to a JavaScript file: script script tag should be placed in HTML page's head script code is stored in a separate . js file JS code can be placed directly in the HTML file's body or head (like CSS) but this is bad style (should separate content, presentation, and behavior 11 <script src ="filename" type="text/ javascript "></script> HTML

Event-driven programming 12 split breaks apart a string into an array using a delimiter can also be used with regular expressions (seen later) join merges an array into a single string, placing a delimiter between them

A JavaScript statement: alert a JS command that pops up a dialog box with a message 13 alert("IE6 detected. Suck-mode enabled."); JS

Event-driven programming 14 you are used to programs start with a main method (or implicit main like in PHP) JavaScript programs instead wait for user actions called events and respond to them event-driven programming: writing programs driven by user events Let's write a page with a clickable button that pops up a "Hello, World" window...

Buttons button's text appears inside tag; can also contain images To make a responsive button or other UI control: choose the control (e.g. button) and event (e.g. mouse 1. click) of interest write a JavaScript function to run when the event occurs attach the function to the event on the control 15 <button>Click me!</button> HTML

JavaScript functions 16 function name() { statement ; statement ; ... statement ; } JS the above could be the contents of example.js linked to our HTML page statements placed into functions can be evaluated in response to user events function myFunction () { alert("Hello!"); alert("How are you?"); } JS <!DOCTYPE html> <html> < head > < title >Event Handler Example </ title > </ head > <body> <input type=" text " id=" nameInput "> < button onclick =" greet ()">Greet</ button > <p id=" greeting "></p> <script> function greet () { const name = document.getElementById (" nameInput ").value; const greeting = `Hello, ${ name }!`; document.getElementById (" greeting "). textContent = greeting ; } </script> </body> </html> Try this code on your machine

Event handlers JavaScript functions can be set as event handlers when you interact with the element, the function will execute onclick is just one of many event HTML attributes we'll use but popping up an alert window is disruptive and annoying A better user experience would be to have the message appear on the page... 17 <element attributes onclick ="function();">... HTML <button onclick =" myFunction ();">Click me!</button> HTML <!DOCTYPE html> <html> < head > < title >Event Handler Example </ title > </ head > <body> <input type=" text " id=" nameInput "> < button onclick =" greet ()">Greet</ button > <p id=" greeting "></p> <script> function greet () { const name = document.getElementById (" nameInput ").value; const greeting = `Hello, ${ name }!`; document.getElementById (" greeting "). textContent = greeting ; } </script> </body> </html> <!DOCTYPE html> <html> <head> <title>Event Handler Example</title> </head> <body> <input type="text" id="nameInput"> <button onclick="greet()">Greet</button> <p id="greeting"></p> <script> function greet() { const name = document.getElementById("nameInput").value; const greeting = `Hello, ${name}!`; document.getElementById("greeting").textContent = greeting; } </script> </body> </html> <!DOCTYPE html> <html> <head> <title>Event Handler Example</title> </head> <body> <input type="text" id="nameInput"> <button onclick="greet()">Greet</button> <p id="greeting"></p> <script> function greet() { const name = document.getElementById("nameInput").value; const greeting = `Hello, ${name}!`; document.getElementById("greeting").textContent = greeting; } </script> </body> </html> <!DOCTYPE html> <html> <head> <title>Event Handler Example</title> </head> <body> <input type="text" id="nameInput"> <button onclick="greet()">Greet</button> <p id="greeting"></p> <script> function greet() { const name = document.getElementById("nameInput").value; const greeting = `Hello, ${name}!`; document.getElementById("greeting").textContent = greeting; } </script> </body> </html> Try this code on your machine

Document Object Model (DOM) most JS code manipulates elements on an HTML page we can examine elements' state e.g. see whether a box is checked we can change state e.g. insert some new text into a div we can change styles e.g. make a paragraph red 18

DOM element objects 19 <!DOCTYPE html> <html> < head > < title >Object Example </ title > </ head > <body> <h1>Object Example </h1> <p id=" objectOutput "></p> <script> // Create a person object const person = { firstName : "John", lastName : " Doe ", age : 30, city: "New York", hobbies: [" reading ", " coding ", " hiking "], isMarried : false }; // Access properties const fullName = person.firstName + " " + person.lastName ; const age = person.age; const firstHobby = person.hobbies [0]; // Add a new property person.occupation = " developer "; // Modify an existing property person.age = 31; // Delete a property delete person.city ; // Check if a property exists const hasOccupation = "occupation" in person ; // Iterate over object properties let personInfo = ""; for (let key in person ) { personInfo += key + ": " + person [ key ] + "\n"; } document.getElementById (" objectOutput "). textContent = ` Full name : ${ fullName } Age: ${ age } First hobby: ${ firstHobby } Occupation: ${ person.occupation } Has occupation: ${ hasOccupation } Person info: ${ personInfo } `; </script> </body> </html> Try this code on your machine

Accessing elements: document.getElementById 20 var name = document.getElementById ("id"); JS <button onclick =" changeText ();">Click me!</button> <span id="output"> replace me</span> <input id="textbox" type="text" /> HTML function changeText () { var span = document.getElementById ("output"); var textBox = document.getElementById ("textbox"); textbox.style.color = "red"; } JS

Accessing elements: document.getElementById 21 document.getElementById returns the DOM object for an element with a given id can change the text inside most elements by setting the innerHTML property can change the text in form controls by setting the value property <!DOCTYPE html> <html> < head > < title > getElementById Example </ title > </ head > <body> <h1 id=" heading "> Welcome !</h1> < button onclick =" changeHeading ()">Change Heading </ button > <script> function changeHeading () { const heading = document.getElementById (" heading "); heading.textContent = "Hello from JavaScript!"; } </script> </body> </html> Try this code on your machine

Changing element style: element.style 22 Attribute Property or style object color color padding padding background-color backgroundColor border-top-width borderTopWidth Font size fontSize Font famiy fontFamily

Preetify 23 function changeText () { //grab or initialize text here // font styles added by JS: text.style.fontSize = "13pt"; text.style.fontFamily = "Comic Sans MS"; text.style.color = "red "; // or pink? } JS <!DOCTYPE html> <html> < head > < title >Change Button Color </ title > </ head > <body> < button id=" myButton ">Click Me</ button > <script> function changeColor () { const button = document.getElementById (" myButton "); button.style.backgroundColor = " lightblue "; // Change to desired color } // Attach event listener to the button on page load window.onload = function () { document.getElementById (" myButton "). addEventListener ("click", changeColor ); } </script> </body> </html> Try this code on your machine

M ore Javascript Syntax 24

Variables variables are declared with the var keyword (case sensitive) types are not specified, but JS does have types ("loosely typed") Number, Boolean, String, Array, Object, Function, Null, Undefined can find out a variable's type by calling typeof 25 var name = expression; JS var clientName = "Connie Client"; var age = 32; var weight = 127.4; JS

Number type integers and real numbers are the same type (no int vs. double) same operators: + - * / % ++ -- = += -= *= /= %= similar precedence to Java many operators auto-convert types: "2" * 3 is 6 26 var enrollment = 99; var medianGrade = 2.8; var credits = 5 + 4 + (2 * 3); JS

Comments (same as Java) identical to Java's comment syntax recall: 4 comment syntaxes HTML:  CSS/JS/PHP: /* comment */ Java/JS/PHP: // comment PHP: # comment 27 // single-line comment /* multi-line comment */ JS

Math object 28 var rand1to10 = Math.floor ( Math.random () * 10 + 1); var three = Math.floor ( Math.PI ); JS methods: abs, ceil, cos , floor, log, max, min, pow , random, round, sin, sqrt , tan properties: E, PI

Special values: null and undefined 29 var ned = null; var benson = 9; // at this point in the code, // ned is null // benson's 9 // caroline is undefined JS undefined : has not been declared, does not exist null : exists, but was specifically assigned an empty or null value Why does JavaScript have both of these?

Logical operators 30 > < >= <= && || ! == != === !== most logical operators automatically convert types: 5 < "7" is true 42 == 42.0 is true "5.0" == 5 is true === and !== are strict equality tests; checks both type and value "5.0" === 5 is false

if/else statement (same as Java) 31 if (condition) { statements; } else if (condition) { statements; } else { statements; } JS identical structure to Java's if/else statement JavaScript allows almost anything as a condition

Boolean type 32 var iLike190M = true; var ieIsGood = "IE6" > 0; // false if ("web devevelopment is great") { /* true */ } if (0) { /* false */ } JS any value can be used as a Boolean " falsey " values: 0, 0.0, NaN , "", null, and undefined " truthy " values: anything else converting a value into a Boolean explicitly: var boolValue = Boolean( otherValue ); var boolValue = !!( otherValue );

for loop (same as Java) 33 var sum = 0; for (var i = 0; i < 100; i++) { sum = sum + i; } JS var s1 = "hello"; var s2 = ""; for ( var i = 0; i < s.length ; i++) { s2 += s1.charAt(i) + s1.charAt(i); } // s2 stores " hheelllloo " JS <!DOCTYPE html> <html> < head > < title > Number Guessing Game</ title > </ head > <body> <p> Guess a number between 1 and 10:</p> <input type=" number " id=" guessInput "> < button onclick =" guessNumber ()"> Guess </ button > <p id=" result "></p> <script> const randomNumber = Math.floor ( Math.random () * 10) + 1; function guessNumber () { const guess = parseInt ( document.getElementById (" guessInput ").value); const resultElement = document.getElementById (" result "); if ( isNaN ( guess )) { resultElement.textContent = " Please enter a number ."; } else if ( guess === randomNumber ) { resultElement.textContent = "Congratulations! You guessed it! "; } else if ( guess < randomNumber ) { resultElement.textContent = " Too low ."; } else { resultElement.textContent = " Too high ."; } } </script> </body> </html> Try this code on your machine

while loops (same as Java) 34 while (condition) { statements; } JS break and continue keywords also behave as in Java do { statements; } while (condition); JS

Popup boxes 35 alert("message"); // message confirm("message"); // returns true or false prompt("message"); // returns user input string JS

Arrays 36 var name = []; // empty array var name = [value, value, ..., value]; // pre-filled name[index] = value; // store element JS var ducks = ["Huey", "Dewey", "Louie"]; var stooges = []; // stooges.length is 0 stooges[0] = "Larry"; // stooges.length is 1 stooges[1] = "Moe"; // stooges.length is 2 stooges[4] = "Curly"; // stooges.length is 5 stooges[4] = " Shemp "; // stooges.length is 5 JS Try this code on your machine <!DOCTYPE html> <html> < head > < title > Array Example </ title > </ head > <body> <h1> Array Example </h1> <p id=" arrayOutput "></p> <script> // Create an array of numbers const numbers = [3, 7, 1, 9, 5]; // Access elements const firstNumber = numbers [0]; const lastNumber = numbers [ numbers.length - 1]; // Modify elements numbers [2] = 4; // Add elements numbers.push (6); // Remove elements numbers.pop(); // Find the index of an element const index = numbers.indexOf (7); // Sort the array numbers.sort (); // Reverse the array numbers.reverse (); // Find the maximum and minimum values const maxNumber = Math.max(... numbers ); const minNumber = Math.min(... numbers ); // Create a new array with a subset of elements const slicedArray = numbers.slice (1, 4); // Join array elements into a string const joinedString = numbers.join (", "); document.getElementById (" arrayOutput "). textContent = ` First number : ${ firstNumber } Last number : ${ lastNumber } Modified array : ${ numbers } Index of 7: ${index} Sorted array : ${ numbers } Reversed array : ${ numbers } Max number : ${ maxNumber } Min number : ${ minNumber } Sliced array : ${ slicedArray } Joined string: ${ joinedString } `; </script> </body> </html>

Array methods 37 var a = [" Stef ", "Jason"]; // Stef , Jason a.push ("Brian"); // Stef , Jason, Brian a.unshift ("Kelly"); // Kelly, Stef , Jason, Brian a.pop (); // Kelly, Stef , Jason a.shift (); // Stef , Jason a.sort (); // Jason, Stef JS array serves as many data structures: list, queue, stack, ... methods: concat , join, pop, push, reverse, shift, slice, sort, splice, toString , unshift push and pop add / remove from back unshift and shift add / remove from front shift and pop return the element that is removed Try this code on your machine <!DOCTYPE html> <html> < head > < title > Arrays , Objects , and Strings Example </ title > </ head > <body> <h1> Arrays , Objects , and Strings</h1> <p id=" arrayOutput "></p> <p id=" objectOutput "></p> <p id=" stringOutput "></p> <script> // Arrays const fruits = [" apple ", "banana", "orange"]; document.getElementById (" arrayOutput "). textContent = fruits.join (", "); // Objects const person = { firstName : "John", lastName : " Doe ", age : 30 }; document.getElementById (" objectOutput "). textContent = person.firstName + " " + person.lastName + ", " + person.age + " years old "; // Strings const greeting = "Hello, World!"; const upperCaseGreeting = greeting.toUpperCase (); document.getElementById (" stringOutput "). textContent = upperCaseGreeting ; </script> </body> </html>

String type methods: charAt , charCodeAt , fromCharCode , indexOf , lastIndexOf , replace , split, substring, toLowerCase , toUpperCase charAt returns a one-letter String (there is no char type) length property (not a method as in Java) Strings can be specified with "" or '' concatenation with + : 1 + 1 is 2, but "1" + 1 is "11" 38 var s = "Connie Client"; var fName = s.substring (0, s.indexOf (" ")); // "Connie" var len = s.length ; // 13 var s2 = 'Melvin Merchant'; JS Try this code on your machine <!DOCTYPE html> <html> < head > < title >String Functions Example </ title > </ head > <body> <h1>String Functions </h1> <p id=" stringOutput "></p> <script> const text = "The quick brown fox jumps over the lazy dog"; // Length of the string const length = text.length ; // Substring const subString = text.substring (4, 10); // Index of a character const indexOfQuick = text.indexOf ("quick"); // Replace a substring const replacedText = text.replace ("fox", "cat"); // Split the string into an array const words = text.split (" "); // To uppercase const upperCaseText = text.toUpperCase (); // To lowercase const lowerCaseText = text.toLowerCase (); // Concatenate strings const newString = "Hello, " + "world!"; document.getElementById (" stringOutput "). textContent = ` Length : ${ length } Substring : ${ subString } Index of "quick": ${ indexOfQuick } Replaced text : ${ replacedText } Words : ${ words } Uppercase : ${ upperCaseText } Lowercase : ${ lowerCaseText } Concatenated string: ${ newString } `; </script> </body> </html>

More about String accessing the letters of a String: 39 var count = 10; var s1 = "" + count; // "10" var s2 = count + " bananas, ah ah ah !"; // "10 bananas, ah ah ah !" var n1 = parseInt ("42 is the answer"); // 42 var n2 = parseFloat (" booyah "); // NaN JS escape sequences behave as in Java: \' \" \& \n \t \\ converting between numbers and Strings: var firstLetter = s[0]; // fails in IE var firstLetter = s.charAt (0); // does work in IE var lastLetter = s.charAt ( s.length - 1); JS

Splitting strings: split and join 40 var s = "the quick brown fox"; var a = s.split (" "); // ["the", "quick", "brown", "fox"] a.reverse (); // ["fox", "brown", "quick", "the"] s = a.join ("!"); // " fox!brown!quick!the " JS split breaks apart a string into an array using a delimiter can also be used with regular expressions (seen later) join merges an array into a single string, placing a delimiter between them

Workshop To create a responsive, interactive product showcase website using HTML, CSS, Bootstrap, and JavaScript. Students will apply their knowledge of these technologies to build a dynamic and engaging user experience . A product list with images, names, prices, and descriptions . Product details page with additional information, images, and reviews . A shopping cart functionality . Responsive design to adapt to different screen sizes . Interactive elements like product filtering, sorting, and search. 41

Solution Creating the Product List Page Product Details Page Implementing Shopping Cart Functionality Responsive Design Adding Interactivity with JavaScript Putting It All Together 42

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