ReasonJun

In TypeScript, an interface is a way to define the structure and shape of an object. It describes the contract that an object must adhere to by specifying the names, types, and optional modifiers of its properties and methods. Interfaces play a crucial role in defining the shape of data and enabling type checking and static analysis in TypeScript. Here's an example of defining an interface in Ty..

In TypeScript, a type guard is a runtime check that allows you to narrow down the type of a value within a conditional block. Type guards enable you to make more precise type inferences based on certain conditions, improving type safety and enabling more expressive and reliable code. Type guards are particularly useful when working with union types or when the TypeScript compiler cannot determin..

In TypeScript, assertion (also known as type assertion or type casting) is a way to inform the TypeScript compiler about the type of a value when the compiler cannot infer it automatically. It allows you to override the default type inference and treat a value as a specific type, even if there is no obvious relationship between the original type and the asserted type. Type assertions are typical..

In TypeScript, type inference refers to the process by which the TypeScript compiler automatically determines the type of a value or expression based on its usage and context. TypeScript's type inference system analyzes the code and infers types for variables, function return values, and other expressions, reducing the need for explicit type annotations in many cases. Here are some key points ab..

/// Any // All types are possible. However, in this case, there is no reason to use typescript, so it is rarely used. let hello3: any = 'Hello world' hello3 = 123 hello3 = false hello3 = null hello3 = {} hello3 = [] hello3= function () {} /// Unknown const z: any = 123 const u: unknown = 123 // When z is changed to u, all errors occur except for 'any'. // In other words, it is better to use 'unk..

Type annotations in TypeScript are used to explicitly specify the type of a variable, function parameter, return value, or any other entity in your code. They provide a way to declare the expected types and enforce type checking at compile-time, allowing you to catch type-related errors early in the development process. Type annotations are written using a syntax that resembles JavaScript, but w..