JavaScript Syntax and Practices (Ravi Tomar, Sarishma Dangi) (Z-Library)

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JavaScript

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JavaScript Syntax and Practices Dr Ravi Tomar Associate Professor, School of Computer Science, University of Petroleum & Energy Studies, Dehradun, India Ms Sarishma Dangi Assistant Professor, Graphic Era University, Dehradun, India

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First Edition published 2022 by CRC Press 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742 and by CRC Press 2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN © 2022 selection and editorial matter, Ravi Tomar & Sarishma Dangi; individual chapters, the contributors CRC Press is an imprint of Taylor & Francis Group, LLC Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged, please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, access www.copyright.com or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. For works that are not available on CCC please contact mpkbookspermissions@tandf.co.uk Trademark notice: Product or corporate names may be trademarks or registered trademarks and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Names: Tomar, Ravi, author. | Dangi, Sarishma, author. Title: JavaScript : syntax and practices / Ravi Tomar, Sarishma Dangi. Description: First edition. | Boca Raton : Chapman & Hall/CRC Press, 2022. | Includes bibliographical references and index. | Summary: “Javascript is the most prominent web programming language in the industry today and has endless capabilities in full stack web applications. JavaScript is most preferred because of its compatibility with all the major browsers and its flexibility with the syntax it holds. Being a Front-end language, JavaScript is also used on the server-side through Node.js. This book focuses on developing the basics concepts of Javascript and enlightening the readers about the horizons that can be accessed using this language. Offers detailed explanation of the core topics Covers both miscellaneous and advanced topics Gives a platform to connect JavaScript to cutting edge technologies such as Cloud, Machine Learning, Internet of Things etc Provides examples to enable ease of learning Includes exercises to get more comfortable with complex code Uses case complete projects with examples This book is primarily aimed at undergraduates and graduates studying web application development. Developers will also find it useful as a handbook”– Provided by publisher. Identifiers: LCCN 2021032161 (print) | LCCN 2021032162 (ebook) | ISBN 9780367641429 (hardback) | ISBN 9780367641474 (paperback) | ISBN 9781003122364 (ebook) Subjects: LCSH: JavaScript (Computer program language) | Object-oriented programming (Computer science) | Programming languages (Electronic computers)--Syntax. | Web site development. Classification: LCC QA76.73.J39 T64 2022 (print) | LCC QA76.73.J39 (ebook) | DDC 005.2/762–dc23 LC record available at https://lccn.loc.gov/2021032161 LC ebook record available at https://lccn.loc.gov/2021032162 ISBN: 978-0-367-64142-9 (hbk) ISBN: 978-0-367-64147-4 (pbk) ISBN: 978-1-003-12236-4 (ebk) Access the companion website: https://www.routledge.com/9780367641429 DOI: 10.1201/9781003122364 Typeset in Palatino by MPS Limited, Dehradun

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To my loving parents, my wonderful partner Manu and my two little princesses Kritika & Vedika. The continued support from my family and friends could make this book possible. - Ravi Tomar To my parents, Rajender and Sushila. I am grateful for your nurturing and contribution which bought me here. I promise you that I will never give up and continue to strive with my brightest light. I will leave a trace in this world, one with your names behind it. Thank you for all the love, light, support, warmth and especially the wings you gave me to fly. - Sarishma Dangi

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Contents Preface.....................................................................................................................xv Acknowledgements ........................................................................................... xvii Authors..................................................................................................................xix 1. Introduction.....................................................................................................1 1.1 Introduction to Web Development................................................... 1 1.2 Client-Side and Server-Side JavaScript ............................................ 3 1.3 Origin, History and Evolution of JavaScript .................................. 4 1.4 Features of JavaScript.......................................................................... 6 1.5 Advantages and Limitations.............................................................. 8 1.6 Structure of Browsers........................................................................ 10 1.7 Saying Hello World to JS.................................................................... 11 1.7.1 Built-In Functions................................................................. 12 1.7.2 Gathering Software .............................................................. 13 1.7.2.1 Examples of Framework, Library and Tools ........................................................................14 1.8 Placement of Code............................................................................. 15 1.9 Exercise ................................................................................................ 17 1.9.1 Theory .................................................................................... 17 1.9.2 True/False ............................................................................. 17 1.9.3 Multiple-Choice Questions ................................................. 18 2. Building the Basics......................................................................................19 2.1 Lexical Structure ................................................................................ 19 2.2 Character Set....................................................................................... 19 2.2.1 Whitespace and Comments................................................ 20 2.2.2 Case Sensitivity..................................................................... 20 2.2.3 Semicolons ............................................................................. 20 2.2.4 Literals.................................................................................... 21 2.2.5 Identifiers ............................................................................... 21 2.2.6 Keywords............................................................................... 21 2.3 Variables .............................................................................................. 22 2.3.1 Variable Declaration and Scope......................................... 22 2.4 Data Types .......................................................................................... 24 2.4.1 Primitive Data Types........................................................... 25 2.4.2 Nonprimitive Data Types ................................................... 27 2.4.3 Constants ............................................................................... 27 2.4.4 Type Casting ......................................................................... 28 2.5 Operators............................................................................................. 29 2.5.1 Arithmetic Operators......................................................... 29 vii

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2.5.2 Comparison Operators ...................................................... 29 2.5.3 Bitwise Operators ............................................................... 31 2.5.4 Logical Operators ............................................................... 31 2.5.5 Assignment Operator ........................................................ 31 2.5.6 Ternary Operator................................................................ 32 2.5.7 Comma Operator................................................................ 33 2.5.8 Typeof Operator ................................................................. 33 2.5.9 Delete Operator .................................................................. 34 2.5.10 Void Operator ..................................................................... 34 2.6 Control Flow Statements .................................................................. 34 2.6.1 Decision Statements ............................................................. 34 2.6.1.1 If Else ......................................................................35 2.6.1.2 Switch Case Statement.........................................36 2.6.2 Loops and Iterations ............................................................ 37 2.6.2.1 For Loop .................................................................37 2.6.2.2 While Loop.............................................................38 2.6.2.3 Do-While Loop......................................................38 2.6.2.4 For-In Loop ............................................................39 2.7 Exercise ................................................................................................ 39 2.7.1 Theory .................................................................................... 39 2.7.2 True/False ............................................................................. 40 2.7.3 Multiple-Choice Questions ................................................. 40 2.8 Demo and Hands-On for Variables and Assignment Operator ........................................................................ 41 2.8.1 Objective ................................................................................ 41 2.8.2 Prerequisite............................................................................ 41 2.8.3 Explore ................................................................................... 42 2.8.3.1 Code Snippet-1 ......................................................42 2.8.3.2 Code Snippet-2 ......................................................42 2.8.3.3 Code Snippet-3 ......................................................43 2.9 Demo and Hands-On for Control Flow Statements ........................................................................................... 43 2.9.1 Objective ................................................................................ 43 2.9.2 Prerequisite............................................................................ 44 2.9.3 Explore ................................................................................... 44 2.9.3.1 Code Snippet-1 ......................................................44 2.9.3.2 Code Snippet-2 ......................................................45 3. Objects............................................................................................................47 3.1 Objects.................................................................................................. 48 3.2 Properties of Objects ......................................................................... 50 3.2.1 Property Configuration Descriptors ................................. 50 3.3 Creating Objects................................................................................. 52 3.4 Objects as Record and Dictionary .................................................. 54 3.5 Operations on Objects....................................................................... 55 viii Contents

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3.5.1 Accessors and Mutators...................................................... 55 3.5.2 Useful Operations and Loops............................................ 57 3.5.3 Object Methods..................................................................... 60 3.5.4 Built-In Object Methods...................................................... 61 3.6 Prototypal Inheritance ...................................................................... 63 3.6.1 Prototype Chaining.............................................................. 64 3.7 Classes ................................................................................................. 65 3.7.1 Constructor, Properties and Methods .............................. 66 3.7.2 Extending Classes ................................................................ 68 3.7.3 Getters and Setters in Classes............................................ 69 3.7.4 Static Members ..................................................................... 70 3.8 Garbage Collection ............................................................................ 71 3.9 Exercise ................................................................................................ 73 3.9.1 Theory .................................................................................... 73 3.9.2 True/False ............................................................................. 73 3.9.3 Multiple-Choice Questions................................................. 74 3.10 Demo and Hands-On for Objects ................................................... 75 3.10.1 Objective .............................................................................. 75 3.10.2 Prerequisite.......................................................................... 75 3.10.3 Explore ................................................................................. 75 3.10.3.1 Code Snippet-1..................................................76 3.10.3.2 Code Snippet-2..................................................77 3.10.3.3 Code Snippet-3..................................................78 4. Functions........................................................................................................81 4.1 Functions in JavaScript ..................................................................... 81 4.2 Function Variable Scope ................................................................... 82 4.3 Function Declaration ......................................................................... 84 4.3.1 Traditional Function Declaration ...................................... 85 4.3.2 Function Expressions........................................................... 85 4.3.3 Arrow Function Expressions.............................................. 86 4.3.3.1 Limitations of Arrow Functions.........................87 4.4 Parameters in a Function.................................................................. 89 4.4.1 Return Keyword in Functions ........................................... 89 4.4.2 Invoking a Function............................................................. 89 4.4.3 Recursion ............................................................................... 90 4.4.4 Closures.................................................................................. 90 4.5 Exercise ................................................................................................ 91 4.5.1 Theory .................................................................................... 91 4.5.2 True/False ............................................................................. 91 4.5.3 Multiple-Choice Questions ................................................. 92 4.6 Demo and Hands-On for Functions............................................... 93 4.6.1 Objective ................................................................................ 93 4.6.2 Prerequisite............................................................................ 93 Contents ix

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4.6.3 Explore ................................................................................... 93 4.6.3.1 Code Snippet-1 ......................................................94 4.6.3.2 Code Snippet-2 ......................................................96 5. Arrays .............................................................................................................99 5.1 Array .................................................................................................... 99 5.2 Properties of Array.......................................................................... 100 5.3 Declaring an Array.......................................................................... 100 5.3.1 Array Literal........................................................................ 101 5.3.2 Using the New Keyword and Array Constructor ....... 101 5.4 Accessing an Array ......................................................................... 102 5.5 Built-In Methods inside Array ...................................................... 103 5.5.1 Accessor Methods .............................................................. 103 5.5.2 Mutator Methods ............................................................... 107 5.5.3 Iterator Methods................................................................. 111 5.5.3.1 Using Fundamental Loops................................112 5.5.3.2 Predefined Iterator Methods.............................112 5.6 Nesting and Multidimensional Arrays........................................ 116 5.7 Sorting................................................................................................ 117 5.8 Points to Ponder .............................................................................. 119 5.9 Exercise .............................................................................................. 120 5.9.1 Theory .................................................................................. 120 5.9.2 True/False ........................................................................... 120 5.9.3 Multiple-Choice Questions............................................... 120 5.10 Demo and Hands-On for Arrays.................................................. 122 5.10.1 Objective............................................................................ 122 5.10.2 Prerequisite........................................................................ 122 5.10.3 Explore ............................................................................... 122 5.10.3.1 Code Snippet-1 ...............................................122 5.10.3.2 Code Snippet-2................................................123 5.10.3.3 Code Snippet-3................................................125 6. Browser Object Model..............................................................................127 6.1 Browser Object Model..................................................................... 127 6.2 Window Object................................................................................. 129 6.2.1 Properties of Window Object........................................... 131 6.2.2 Methods of Window Object ............................................. 132 6.3 History Object................................................................................... 134 6.3.1 Properties of History Object............................................. 135 6.3.2 Methods of History Object ............................................... 135 6.4 Navigator Object .............................................................................. 136 6.4.1 Properties and Methods of Navigator Object.................................................................................... 137 6.5 Location Object................................................................................. 138 6.5.1 Properties of Location Object........................................... 138 x Contents

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6.5.2 Methods of Location Object ............................................. 139 6.6 Screen Object .................................................................................... 139 6.6.1 Properties of Screen Object............................................... 139 6.7 Document Object.............................................................................. 140 6.8 Exercise .............................................................................................. 140 6.8.1 Theory .................................................................................. 140 6.8.2 True/False ........................................................................... 140 6.8.3 Multiple-Choice Questions ............................................... 141 6.9 Demo and Hands-On for BOM..................................................... 142 6.9.1 Objective .............................................................................. 142 6.9.2 Prerequisites ........................................................................ 142 6.9.3 Explore ................................................................................. 142 6.9.3.1 Code Snippet-1 ....................................................142 6.9.3.2 Code Snippet-2 ....................................................143 7. Document Object Model..........................................................................145 7.1 Document Object Model (DOM) .................................................. 145 7.2 Relationship between BOM, DOM and JavaScript .......................................................................................... 148 7.3 Understanding DOM Tree and Nodes ........................................ 151 7.3.1 Properties of Node Object ................................................ 153 7.3.2 Method of Node Object .................................................... 154 7.4 Document Object ............................................................................. 155 7.4.1 Properties of Document Object ....................................... 155 7.4.2 Methods for Document Object ........................................ 156 7.5 Elements in DOM ............................................................................ 157 7.5.1 Properties of Element Object ........................................... 157 7.5.2 Methods for Element Object ............................................ 158 7.6 Accessing Elements in the DOM .................................................. 159 7.7 Event Handling Using DOM......................................................... 162 7.8 Exercise .............................................................................................. 164 7.8.1 Theory .................................................................................. 164 7.8.2 True/False ........................................................................... 164 7.8.3 Multiple-Choice Questions............................................... 164 7.9 Demo and Hands-On DOM .......................................................... 165 7.9.1 Objective .............................................................................. 165 7.9.2 Prerequisite.......................................................................... 165 7.9.3 Explore ................................................................................. 166 7.9.3.1 Code Snippet-1....................................................166 7.9.3.2 Code Snippet-2....................................................167 7.9.3.3 Code Snippet-3....................................................169 7.9.3.4 Code Snippet-4....................................................170 7.10 Demo and Hands-On for Event Delegation ............................... 174 7.10.1 Objective ............................................................................ 174 7.10.2 Prerequisite........................................................................ 174 Contents xi

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7.10.3 Explore ............................................................................... 175 7.10.3.1 Code Snippet-1................................................175 7.10.3.2 Code Snippet-2................................................177 8. Standard Built-In Objects ........................................................................179 8.1 Built-In Objects ................................................................................. 179 8.1.1 Fundamental Objects ......................................................... 180 8.1.1.1 Object Prototype..................................................180 8.1.1.2 Function Object ...................................................181 8.1.1.3 Boolean Object.....................................................181 8.1.1.4 Symbol Object......................................................183 8.1.2 Error Objects ....................................................................... 184 8.1.3 Number and Dates............................................................. 184 8.1.3.1 Number Object ....................................................184 8.1.3.2 Date Object...........................................................186 8.1.3.3 Math Object..........................................................188 8.1.4 Text or String Processing.................................................. 190 8.1.4.1 String Object ........................................................190 8.1.4.2 RegExp Object .....................................................193 8.1.5 Keyed Collections............................................................... 195 8.1.5.1 Map Object ...........................................................195 8.1.5.2 Set Object..............................................................196 8.1.6 Indexed Collections............................................................ 197 8.1.6.1 Array Object.........................................................197 8.1.7 Structured Data................................................................... 199 8.1.8 Value Properties ................................................................. 199 8.1.9 Function Properties............................................................ 200 8.2 Exercise .............................................................................................. 201 8.2.1 Theory .................................................................................. 201 8.2.2 True/False ........................................................................... 202 8.2.3 Multiple-Choice Questions ............................................... 202 8.3 Demo and Hands-On for Loops ................................................... 203 8.3.1 Objective .............................................................................. 203 8.3.2 Prerequisite.......................................................................... 203 8.3.3 Explore ................................................................................. 203 8.3.3.1 Code Snippet-1 ....................................................203 8.3.3.2 Code Snippet-2 ....................................................204 8.3.3.3 Code Snippet-3 ....................................................205 8.4 Demo and Hands-On for Hoisting............................................... 207 8.4.1 Objective .............................................................................. 207 8.4.2 Prerequisite.......................................................................... 207 8.4.3 Explore ................................................................................. 207 8.4.3.1 Code Snippet-1 ....................................................208 8.4.3.2 Code Snippet-2 ....................................................209 xii Contents

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9. Validation, Error Handling and Cookies .............................................211 9.1 Validation .......................................................................................... 211 9.1.1 Server- and Client-Side Validation ................................. 212 9.1.2 Using Built-In Form Validation....................................... 212 9.1.3 Using JavaScript for Validation....................................... 214 9.2 Error Handling ................................................................................. 215 9.2.1 Error Object ......................................................................... 216 9.2.2 Try-Catch Block .................................................................. 217 9.2.3 Finally Block........................................................................ 218 9.2.4 Throw Statement ................................................................ 219 9.3 Cookies .............................................................................................. 219 9.4 Strict Mode........................................................................................ 220 9.5 Best Practices .................................................................................... 222 9.6 Exercise .............................................................................................. 224 9.6.1 Theory .................................................................................. 224 9.6.2 True/False ........................................................................... 225 9.6.3 Multiple-Choice Questions ............................................... 225 9.7 Demo and Hands-On for Form Validation and Cookies. ........ 226 9.7.1 Objective .............................................................................. 226 9.7.2 Prerequisite.......................................................................... 226 9.7.3 Explore ................................................................................. 226 9.7.3.1 Code Snippet-1 ....................................................226 10. Miscellaneous Case Studies ....................................................................229 10.1 Case Study-1: Introduction to Fetch API................................... 229 10.1.1 Objective .......................................................................... 229 10.1.2 Prerequisite...................................................................... 229 10.1.3 Explore ............................................................................. 230 10.1.3.1 Code Snippet-1 ..............................................230 10.2 Case Study-2: Integrating MongoDB in Cloud ........................ 231 10.2.1 Objective .......................................................................... 231 10.2.2 Prerequisite...................................................................... 231 10.2.2.1 MongoDB Cloud Connection .....................231 10.2.2.2 Docker Container for Node.js.....................232 10.2.3 Agenda ............................................................................. 233 10.2.4 Explore ............................................................................. 233 10.2.4.1 Front-End Script for Invoking Our Custom APIs..................................................233 10.2.4.2 Code Walkthrough .......................................234 10.2.4.3 Creating Node.js Backend ...........................234 10.3 Case Study-3: Visualizing Graphs with JavaScript......................................................................................... 237 10.3.1 Objective .......................................................................... 237 10.3.2 Prerequisite...................................................................... 237 10.3.3 Agenda ............................................................................. 237 Contents xiii

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10.3.4 Explore ............................................................................. 237 10.3.5 Front-End Script for Invoking Our Custom APIs ................................................................... 237 10.4 Case Study-4: Integrating Firebase Auth................................... 239 10.4.1 Objective .......................................................................... 239 10.4.2 Background ..................................................................... 239 10.4.3 Prerequisite...................................................................... 239 10.4.4 Agenda ............................................................................. 240 10.4.5 Explore ............................................................................. 240 10.4.5.1 Creating a Login Page .................................240 10.4.5.2 Code Walkthrough .......................................241 10.4.5.3 Creating Home Page ....................................242 10.4.5.4 Code Walkthrough .......................................243 References............................................................................................................245 Index .....................................................................................................................253 xiv Contents

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Preface JavaScript emerged as a quick fix language, but in the last decade, it has embedded and closely integrated itself with the web. It is difficult to avoid JavaScript while working with dynamic web content. Due to its prevalence, it was soon accepted as a general-purpose language for working in both client- and server-side programming. The popularity, ease of use and rapid adoption of JavaScript made imperative for us to discuss it for novice as well as experienced users. This book aims at covering the JavaScript language basics and fundamentals to help readers strengthen their programming. It is designed to explain the language in the simplest possible words with a comprehensive hands-on approach toward learning by practice. Every chapter in the book is supplemented with demo code, which will compel you to practically test what you read in the chapters. These live exercises allow easier learning for readers by switching swiftly between theory and practice. Lastly, we provide extended case studies that aim to assist readers in exploring more dimensions of JavaScript as a language. There is so much you can cover in a book, right? With that said, we hope that this book offers you an amazing experience at hands-on learning, and you can come back to it whenever you need a little refreshment. Ravi Tomar Sarishma Dangi xv

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Acknowledgements Writing a book resembles a marathon. It is a long and tedious process. This work would not have been the way it is if not for the support provided by two very special individuals. A special thanks to Dibyasom Puhan, Undergraduate student at School of Computer Science, University of Petroleum and Energy Studies, Dehradun for his untiring support in developing hands-on code and flawless execution of work. Dibyasom is always a dedicated and sincere individual to trust upon. Other big thanks go to Kamakshi Negi for her contribution and support throughout the writing of this book. Many times, it is hard to move on. In those moments, she gave us light and never hesitated to step in and contribute to this work. We are humbled to have Dibyasom and Kamakshi with us. We wish them joy, success, and warmth wherever they go in the future. Needless to say, we are always a phone call away. xvii

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Authors Dr Ravi Tomar is currently working as Associate Professor in the School of Computer Science at the University of Petroleum & Energy Studies, Dehradun, India. He is an experienced academician with a demonstrated history of working in the higher education industry. Skilled in Programming, Computer Networking, Stream Processing, Python, Oracle Database, C++, Core Java, J2EE, RPA and CorDApp. His research interests include Wireless Sensor Networks, Image Processing, Data Mining and Warehousing, Computer Networks, Big Data Technologies and VANET. He has authored 60+ papers in different research areas, filled four Indian patent, edited 5 books, and have authored 4 books. He has delivered Training to corporations nationally and internationally on Confluent Apache Kafka, Stream Processing, RPA, CordaApp, J2EE and IoT to clients like KeyBank, Accenture, Union Bank of Philippines, Ernst and Young and Deloitte. Dr Tomar is officially recognized as Instructor for Confluent and CordApp. He has conducted various international conferences in India, France and Nepal. He has been awarded a Young Researcher Award in Computer Science and Engineering by RedInno, India in 2018, Academic Excellence and Research Excellence Award by UPES in 2021 and conferred by Research Excellence Award 2021 by Hon’ble Chief Minister of Uttarakhand State, India. Ms Sarishma Dangi is currently working in the capacity of Assistant Professor in the Computer Science and Engineering department at Graphic Era University, Dehradun, India. She is a Google Cloud Certified Professional Cloud Architect specialized in the area of virtualization and cloud computing. She is a bright young enthusiast driven towards innovative research work and dedicated to imparting quality education to the higher education industry. She has authored many research papers in recognized journals and has authored a book on “Mobile Cloud Computing: Principles and Paradigms”. Her research interests include blockchain, virtualization, vehicular ad hoc networks and live memory forensics. She is currently pursuing her PhD with full rigour. xix