class Point { // Overloads constructor(x: number, y: string); constructor(s: string); constructor(xs: any, y?: any) { // TBD }} 但类构造函数签名与函数签名之间也有一些区别：构造函数不能有类型参数（关于类型参数，回想下泛型里的内容），这些属于外层的类声明，我们稍后就会学习到。
On page 64 of the language specification (v 0.8), there are statements describing constructor overloads, but there wasn't any sample code given.在语言规范(v 0.8)的第64页上,有描述构造函数重载的语句,但是没有给出任何示例代码。 I'm trying out a really basic class declaration right now;我现在...
Ts扩展了js类,包括类型参数(type parameters)、实现子语句(implements clauses)、可访问性修饰符(accessibility modifiers)、成员变量声明(member variable declarations)和构造器参数特性声明(parameter property declarations in constructors)。 8.1 类声明(Class Declarations) 类声明声明一个类类型(class type)和一个构造...
class Point {x: number;y: number;// Normal signature with defaultsconstructor(x = 0, y = 0) {this.x = x;this.y = y;}}复制代码 class Point {// Overloadsconstructor(x: number, y: string);constructor(s: string);constructor(xs: any, y?: any) {// TBD}}复制代码 但类构造函数签...
interface Shape { x: number; y: number; height: number; width: number; } class Square { public x: number; public y: number; public height: number; public width: number; constructor(); constructor(obj: Shape); constructor(obj?: any) { this.x = obj?.x ?? 0; this.y = obj?.y ...
class BadGreeter { name: string; // Property 'name' has no initializer and is not definitely assigned in the constructor. } class GoodGreeter { name: string; constructor() { this.name = "hello"; } } 注意,字段需要在构造函数自身进行初始化。TypeScript 并不会分析构造函数里你调用的方法,进而...
class Point { x: number; y: number; // Normal signature with defaults constructor(x = 0, y = 0) { this.x = x; this.y = y; } } 代码语言:javascript 代码运行次数:0 运行 AI代码解释 class Point { // Overloads constructor(x: number, y: string); constructor(s: string); construct...
因此多用union少用overload吧 control flow analysis && narrow 当使用union来实现函数重载时,ts可以通过control flow analysis,将union type narrowing到某个具体的类型,可以帮助我们保证我们的实现更加安全。 function padLeft(padding: number | string, input: string) { ...
class Box { public x: number; public y: number; public height: number; public width: number; constructor(obj: IBox) { this.x = obj.x; this.y = obj.y; this.height = obj.height; this.width = obj.width; } constructor() {
classBook {pages:number;constructor(totalPages:number) {this.pages = totalPages;} isLastPageFunction() {returnfunction(currentPage:number){// ❌ 'this' here implicitly has type 'any' because it does not have a type annotation.returnthis.page...