The TypeScript Type System: The Benefits and Uses of Strong Types

introduction

In the previous article "TypeScript Getting Started Guide: Transition from JS to TS" , it has been explained to everyone that TypeScript is a statically typed programming language, and it 类型系统is one of its important features. TypeScript's type system can provide some powerful advantages that can help developers write 更健壮, 更可维护and 更易于理解code.

From this article, we will officially enter the learning stage of TS, let's work together!

Advantages of strong typing

better one代码可读性

• TypeScript's static type system can make code easier to understand.
• By checking types at compile time, you can ensure that the behavior of your code is predictable and understandable.
• Developers can save the trouble of knowing variable types when reading the code, so they can focus more on business logic.

  // 字符串
  let a: string = '变量a';
  

When we see the above TS code that defines variables, we will find that TS adds the data type when declaring the variable, so that when the developer gets the code, the understanding of the variable will be clear at a glance without spending a lot of money. It takes time to look through the definition of code traceability variables. The readability of the code is improved, and when compiling, the IDE can also perform type checking according to the defined data type, so that developers can avoid problems caused by data type assignment errors.

better one代码可维护性

• TypeScript's type system can help developers find potential errors in their code more easily, because TypeScript can catch many type errors at compile time. This type constraint makes the code easier to debug and maintain.

better one代码重构能力

• TypeScript's type system helps developers make changes more quickly and safely when refactoring code.
• TypeScript can detect type errors at compile time and provides useful autocompletion, refactoring, and renaming features, reducing the possibility of problems.

better one代码可靠性

• TypeScript's type system prevents common programming errors such as type mismatches, null values, and undefined variables. This kind of type constraint can make the code more reliable, and can greatly reduce the risk of fatal errors.

better one代码重用能力

• TypeScript's type system can help developers reuse code better, because it can detect errors in the code at compile time, making the code more modular and reusable, and reducing the number of repeated codes.

How to use

declare variable type

• The basic types in TypeScript include: string, number, boolean, null, undefined, symbol, , 元组, 枚举(enum).任意值(any)

• 可以使用Type annotations or 类型推断to define the type of the variable.

• In TypeScript, you can use keywords to declare the data type of a variable, for example:

  let num: number = 10;
  let str: string = "hello";
  let arr: number[] = [1, 2, 3];
  let obj: {
        
        
      name: string,
      age: number
  } = {
        
        
      name: "Tom",
      age: 18
  };
  // 枚举
  enum Color {
        
        
      Red,
      Green,
      Blue
  }
  let c: Color = Color.Green;
  // 元组类型:元组类型允许开发者指定数组中每个元素的类型和数量。
  let person: [string, number] = ['Tom', 18];
  

• In addition to the variable types declared above, there are many others, you can refer to the TypeScript Chinese manual

Function parameter and return type

• In TypeScript, you can not only declare variable types for variables, but also specify data types for function parameters and return values, for example:

  // 接收类型为 number 的 x 和 y ，返回 x+y 的值（number）
  function add(x: number, y: number): number {
        
        
      return x + y;
  }
  

type alias

• Type aliases can be used to create reusable types, for example:

  type User = {
        
        
      name: string,
      age: number
  };
  let user: User = {
        
        
      name: "Tom",
      age: 18
  };
  

Generic types (understand)

• Generic types in TypeScript can provide flexible data type support when creating reusable code, such as:

  function identity(arg: T): T {
        
        
      return arg;
  }
  let output = identity("hello");
  console.log(output); // 输出：hello
  

Summarize

In summary, TypeScript's type system provides some powerful tools that help developers create more robust, reliable, maintainable, and understandable code. Developers can flexibly use TypeScript's type system when writing code, thereby improving code quality and development efficiency.