// 抛出异常的函数永远不会有返回值functionerror(message:string):never{thrownewError(message);}// 空数组,而且永远是空的constempty:never[]=[] 数组。用法示例: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 constlist:Array<number>=[1,2,3]constlist:number[]=[1,2,3] 元组。表示一个已知元...
number、string、boolean、Symbol、Array、Tuple、enum、object、never、void、null 和 undefined、any #、type 和 interface 用interface 描述数据结构,用 type 描述类型 type 可以作用于原始值,联合类型,元组以及其它任何你需要手写的类型 它并不会真的创建一个新的名字,当你在编译器上将鼠标悬停在定义为该类型别名定...
: number, id: number): string { return name + id; } // 默认参数 function createUserId(name: string = 'Semlinker', age?: number, id: number): string { return name + id; } 剩余参数 代码语言:javascript 代码运行次数:0 运行 AI代码解释 function push(array, ...items) { items.forEach...
//给原始类型起个小名type UserName =string; let userName: UserName= '陈皮';//还可以是函数type GetString = () =>string; let getString: GetString= () =>{return'i am string'; } let result=getString();//创建一个新的类型type Name ={ realname: string; nickname: string; } let name: ...
默认参数 type A<T=string> = Array<T> 泛型支持函数嵌套 比如: type CutTail<Tuple extends any[]> = Reverse<CutHead<Reverse<Tuple>>>; 如上代码中, Reverse 是将参数列表反转,CutHead 是将数组第一项切掉。因此 CutTail 的意思就是将传递进来的参数列表反转,切掉第一个参数,然后反转回来。换句话说就...
function getVersion(version:string) {if (!version) {version = "1.0.0";}return version;}console.log(getVersion("1.0.1")); 使用常见配置选项 {"compilerOptions": {"target": "ES6", // 目标语言的版本"removeComments": true, // 删除注释"outDir": "./dist/", // 编译输出路径"sourceMap": ...
let name: string = "Semliker";// ES5:var name = 'Semlinker'; 2.4 Array 类型 let list: number[] = [1, 2, 3];// ES5:var list = [1,2,3];let list: Array<number> = [1, 2, 3]; // Array<number>泛型语法// ES5:var list = [1,2,3]; ...
declare let array: string[] | number[]; array.filter(x => !!x); // ~~~ error! // This expression is not callable. // Each member of the union type '...' has signatures, // but none of those signatures are compatible // with each other. In this example, TypeScript would ...
classifiableNames = createMap<string>(); symbolCount = 0; skipTransformFlagAggregation = file.isDeclarationFile; Symbol = objectAllocator.getSymbolConstructor(); if (!file.locals) { bind(file); file.symbolCount = symbolCount; file.classifiableNames = classifiableNames; ...
// 数组(Array) let list: number[] = [1, 2, 3]; let list: Array<number> = [1, 2, 3]; // 元组(Tuple) // Declare a tuple type let x: [string, number]; // Initialize it x = ["hello", 10]; // OK // Initialize it incorrectly x = [10, "hello"]; // Error // 使...