Scott A.D., MacDonald M., Powers S. - JavaScript Cookbook, 3rd Edition [2021, PDF/EPUB, ENG] + code

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Оглавление

Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Part I. The JavaScript Language
1. Setting Up a Development Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Choosing a Code Editor 2
1.2 Using the Developer Console in Your Browser 3
1.3 Running Blocks of Code in the Developer Console 7
1.4 Using Strict Mode to Catch Common Mistakes 9
1.5 Filling in HTML Boilerplate with Emmet Shortcuts 11
1.6 Installing the npm Package Manager (with Node.js) 13
1.7 Downloading a Package with npm 16
1.8 Updating a Package with npm 20
1.9 Setting Up a Local Test Server 21
1.10 Enforcing Code Standards with a Linter 24
1.11 Styling Code Consistently with a Formatter 28
1.12 Experimenting in a JavaScript Playground 31
2. Strings and Regular Expressions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.1 Checking for an Existing, Nonempty String 35
2.2 Converting a Numeric Value to a Formatted String 38
2.3 Inserting Special Characters 40
2.4 Inserting Emojis 42
2.5 Using Template Literals for Clearer String Concatenation 43
2.6 Performing a Case-Insensitive String Comparison 45
2.7 Checking If a String Contains a Specific Substring 46
2.8 Replacing All Occurrences of a String 47
2.9 Replacing HTML Tags with Named Entities 48
2.10 Using a Regular Expression to Replace Patterns in a String 49
2.11 Extracting a List from a String 52
2.12 Finding All Instances of a Pattern 54
2.13 Removing Whitespace from the Beginning and End of a String 57
2.14 Converting the First Letter of a String to Uppercase 58
2.15 Validating an Email Address 59
3. Numbers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.1 Generating Random Numbers 61
3.2 Generating Cryptographically Secure Random Numbers 63
3.3 Rounding to a Specific Decimal Place 65
3.4 Preserving Accuracy in Decimal Values 66
3.5 Converting a String to a Number 68
3.6 Converting a Decimal to a Hexadecimal Value 70
3.7 Converting Between Degrees and Radians 71
3.8 Calculating the Length of a Circular Arc 71
3.9 Manipulating Very Large Numbers with BigInt 72
4. Dates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.1 Getting the Current Date and Time 75
4.2 Converting a String to a Date 77
4.3 Adding Days to a Date 79
4.4 Comparing Dates and Testing Dates for Equality 80
4.5 Calculating the Time Elapsed Between Two Dates 82
4.6 Formatting a Date Value as a String 84
5. Arrays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.1 Checking If an Object Is an Array 88
5.2 Iterating Over All the Elements in an Array 88
5.3 Checking If Two Arrays Are Equal 90
5.4 Breaking Down an Array into Separate Variables 93
5.5 Passing an Array to a Function That Expects a List of Values 94
5.6 Cloning an Array 95
5.7 Merging Two Arrays 97
5.8 Copying a Portion of an Array by Position 98
5.9 Extracting Array Items That Meet Specific Criteria 100
5.10 Emptying an Array 101
5.11 Removing Duplicate Values 102
5.12 Flattening a Two-Dimensional Array 103
5.13 Searching Through an Array for Exact Matches 104
5.14 Searching Through an Array for Items That Meet Specific Criteria 105
5.15 Removing or Replacing Array Elements 107
5.16 Sorting an Array of Objects by a Property Value 108
5.17 Transforming Every Element of an Array 109
5.18 Combining an Array’s Values in a Single Calculation 110
5.19 Validating Array Contents 112
5.20 Creating a Collection of Nonduplicated Values 113
5.21 Creating a Key-Indexed Collection of Items 114
6. Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
6.1 Passing a Function as an Argument to Another Function 117
6.2 Using Arrow Functions 121
6.3 Providing a Default Parameter Value 124
6.4 Creating a Function That Accepts Unlimited Arguments 125
6.5 Using Named Function Parameters 126
6.6 Creating a Function That Stores its State with a Closure 129
6.7 Creating a Generator Function That Yields Multiple Values 131
6.8 Reducing Redundancy by Using Partial Application 135
6.9 Fixing this with Function Binding 138
6.10 Implementing a Recursive Algorithm 141
7. Objects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
7.1 Checking if an Object Is a Certain Type 145
7.2 Using an Object Literal to Bundle Data 147
7.3 Checking If an Object Has a Property 150
7.4 Iterating Over All the Properties of an Object 152
7.5 Testing for an Empty Object 154
7.6 Merging the Properties of Two Objects 155
7.7 Customizing the Way a Property Is Defined 156
7.8 Preventing Any Changes to an Object 159
7.9 Intercepting and Changing Actions on an Object with a Proxy 161
7.10 Cloning an Object 164
7.11 Making a Deep Copy of an Object 166
7.12 Creating Absolutely Unique Object Property Keys 168
7.13 Creating Enums with Symbol 170
8. Classes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
8.1 Creating a Reusable Class 173
8.2 Adding Properties to a Class 177
8.3 Giving a Class a Better String Representation 182
8.4 Using the Constructor Pattern to Make a Custom Class 183
8.5 Supporting Method Chaining in Your Class 186
8.6 Adding Static Methods to a Class 188
8.7 Using a Static Method to Create Objects 190
8.8 Inheriting Functionality from Another Class 192
8.9 Organizing Your JavaScript Classes with Modules 197
9. Asynchronous Programming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
9.1 Updating the Page During a Loop 202
9.2 Using a Function That Returns a Promise 204
9.3 Promisifying an Asynchronous Function That Uses a Callback 208
9.4 Executing Multiple Promises Concurrently 211
9.5 Waiting for a Promise to Finish with Await and Async 214
9.6 Creating an Asynchronous Generator Function 218
9.7 Using a Web Worker to Perform a Background Task 220
9.8 Adding Progress Support to a Web Worker 224
10. Errors and Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
10.1 Catching and Neutralizing an Error 227
10.2 Catching Different Types of Errors 230
10.3 Catching Asynchronous Errors 232
10.4 Detecting Unhandled Errors 233
10.5 Throwing a Standard Error 237
10.6 Throwing a Custom Error 239
10.7 Writing Unit Tests for Your Code 241
10.8 Tracking Test Code Coverage 247
Part II. JavaScript in the Browser
11. Browser Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
11.1 Debugging JavaScript 253
11.2 Analyzing Runtime Performance 255
11.3 Identifying Unused JavaScript 257
11.4 Using Lighthouse to Measure Best Practices 259
12. Working with HTML. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
12.1 Accessing a Given Element and Finding Its Parent and Child Elements 263
12.2 Traversing the Results from querySelectorAll() with forEach() 266
12.3 Adding Click Functionality to an Element 267
12.4 Finding All Elements That Share an Attribute 269
12.5 Accessing All Elements of a Specific Type 269
12.6 Discovering Child Elements Using the Selectors API 272
12.7 Changing an Element’s Class Value 273
12.8 Setting an Element’s Style Attribute 274
12.9 Adding Text to a New Paragraph 276
12.10 Inserting a New Element in a Specific DOM Location 278
12.11 Checking If a Checkbox Is Checked 279
12.12 Adding Up Values in an HTML Table 280
12.13 Deleting Rows from an HTML Table 283
12.14 Hiding Page Sections 285
12.15 Creating Hover-Based Pop-Up Info Windows 287
12.16 Validating Form Data 289
12.17 Highlighting Form Errors and Accessibility 292
12.18 Creating an Accessible Automatically Updated Region 298
13. Fetching Remote Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
13.1 Requesting Remote Data with Fetch 301
13.2 Using XMLHttpRequest 305
13.3 Submitting a Form 306
13.4 Populating a Selection List from the Server 310
13.5 Parsing Returned JSON 314
13.6 Fetching and Parsing XML 316
13.7 Sending Binary Data and Loading into an Image 318
13.8 Sharing HTTP Cookies Across Domains 319
13.9 Using Websockets to Establish a Two-Way Communication Between
Client and Server 320
13.10 Long Polling a Remote Data Source 322
14. Data Persistence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
14.1 Persisting Information with Cookies 325
14.2 Using sessionStorage for Client-Side Storage 328
14.3 Creating a localStorage Client-Side Data Storage Item 334
14.4 Persisting Larger Chunks of Data on the Client Using IndexedDB 338
14.5 Simplifying IndexedDB with a Library 341
15. Working with Media. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
15.1 Adding JavaScript to SVG 345
15.2 Accessing SVG from a Web Page Script 348
15.3 Creating an SVG Bar Chart with D3 350
15.4 Integrating SVG and the Canvas Element in HTML 354
15.5 Running a Routine When an Audio File Begins Playing 356
15.6 Controlling Video from JavaScript with the video Element 357
16. Writing Web Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
16.1 Bundling JavaScript 361
16.2 JavaScript and the Mobile Web 363
16.3 Writing a Progressive Web Application 366
16.4 Testing and Profiling a Progressive Web Application 373
16.5 Getting the Value of the Current URL 377
16.6 Redirecting a URL 379
16.7 Copying Text to a User’s Clipboard 380
16.8 Enabling a Mobile-Like Notification in the Desktop Browser 382
16.9 Loading a File Locally in the Browser 385
16.10 Extending the Possible with Web Components 388
16.11 Choosing a Front-End Framework 391
Part III. Node.js
17. Node Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
17.1 Managing Node Versions with Node Version Manager 397
17.2 Responding to a Simple Browser Request 400
17.3 Interactively Trying Out Node Code Snippets with REPL 402
17.4 Reading and Writing File Data 405
17.5 Getting Input from the Terminal 410
17.6 Getting the Path to the Current Script 412
17.7 Working with Node Timers and Understanding the Node Event Loop 413
18. Node Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
18.1 Searching for a Specific Node Module via npm 420
18.2 Converting Your Library into a Node Module 421
18.3 Taking Your Code Across Module Environments 422
18.4 Creating an Installable Node Module 425
18.5 Writing Multiplatform Libraries 431
18.6 Unit Testing Your Modules 435
19. Managing Node. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
19.1 Using Environment Variables 439
19.2 Managing Callback Hell 441
19.3 Accessing Command-Line Functionality Within a Node Application 444
19.4 Passing Command-Line Arguments 447
19.5 Creating a Command-Line Utility with Help from Commander 448
19.6 Keeping a Node Instance Up and Running 450
19.7 Monitoring Application Changes and Restarting During Local
Development 452
19.8 Scheduling Repeat Tasks 453
19.9 Testing the Performance and Capability of Your WebSockets Application 455
20. Remote Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457
20.1 Fetching Remote Data 457
20.2 Screen Scraping 459
20.3 Accessing JSON-Formatted Data via a RESTful API 461
21. Building Web Applications with Express. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465
21.1 Using Express to Respond to Requests 465
21.2 Using the Express-Generator 469
21.3 Routing 474
21.4 Working with OAuth 476
21.5 OAuth 2 User Authentication with Passport.js 486
21.6 Serving Up Formatted Data 491
21.7 Building a RESTful API 492
21.8 Building a GraphQL API 496
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501