Refactoring TypeScript电子书

Preface

About the Book

About the Author

Learning Objectives

Audience

Approach

Chapter 1

Introduction

About TypeScript

What Is It?

What's All the Fuss About?

TypeScript versus JavaScript

Why I Chose TypeScript for This Book

What Is Refactoring?

Let's Define It

Our Approach

Design Patterns

Why Refactor at All?

Slow Development

Saving Money

Navy SEALS Get It

Being a Craftsman

Case Study #1

Case Study #2

When Should I Refactor?

The Boy Scout Rule

Repetitive Work

Difficulty Adding Features

In the End

Chapter 2

Null Checks Everywhere!

Identification

Billion-Dollar Mistake

Example

Is It That Bad?

Non-Nullable Types

Null Object Pattern

Empty Collections

Fixing It Up

Take 2

What About Objects?

Special Case Pattern

Situation

An Order Class That Needs to Be Refactored

Refactoring the Order Class

Chapter 3

Wordy Conditionals

Identification

A Little Bit of This, a Little Bit of That

Misbehaving Conditionals

Combining Conditionals

Situation

The Code

Guideline

Extracting Methods from Conditionals

What's Wrong Here?

The Fix

Extracting Conditional Logic to Explicit Classes

Let's Get Classy

SRP

Using It

Pipe Classes

Your Classes Might Be Doing Too Much...

Piping Our Logic

Bonus Refactor

Chapter 4

Nested Conditionals

Identification

A Monster

A Closer Look

Guard Clauses

Scenario

Fail Fast

Fixing It Up

Gate Classes

Scenario

Gate Classes to the Rescue

Useful for Web APIs

Chapter 5

Primitive Overuse

Identification

What's Wrong Here?

Value Objects

Scenario

Initial Refactor

Addressing Primitives

Creating Our Object

Moving Along

Immediate Validation

Deceptive Booleans

Scenario

New Business Rules

More Rules...

Is It Really That Bad?

Just Use Enums

Strategy Pattern

Chapter 6

Lengthy Method Signatures

Identification

The Slippery Slope of Optional Parameters

The Issue

Guidelines

Creating a Reusable Private Method

A Simple Example

Creating Semantically Meaningful Methods

A Brief Look at Some Advanced Solutions

Extracting Data Objects

Extraction

Chapter 7

Methods That Never End

Identification

When Is a Method Too Long?

Give It a Name

Being Strategic

Chapter 8

Dumping Grounds

Identification

Object-Oriented?

The Great Debate

Coupling

Warning Sign

One of These Things Is Not Like The Others

You Have Mail

Breaking It Up

Keep Separate Things Separate

Speak or Listen

CQRS

Read and Write

Next Steps

Commands

Queries

Conclusion

A Word of Caution

Chapter 9

Messy Object Creation

Identification

Factory Functions

Functions versus Static Methods

Combining Refactoring Techniques

Complexity Remains...

Building It

The Builder Pattern

One Last Improvement

Chapter 10

Conclusion

This Is Just The Beginning!