let someArray = [1, "string",false];for(let entry of someArray) { console.log(entry);//1, "string", false} 二、for..in 方法 这个方法要注意和for..of的区别,for..in遍历的值是数组的索引 let list = [4, 5, 6];//for infor(let iinlist) { console.log(i);//"0", "1", "2...
functionLogOutput(tarage:Function,key:string,descriptor:any){letoriginalMethod=descriptor.value;letnewMethod=function(...args:any[]):any{letresult:any=originalMethod.apply(this,args);if(!this.loggedOutput){this.loggedOutput=newArray<any>();}this.loggedOutput.push({method:key,parameters:args,outpu...
Besides object types (class, interface, literal and array), you can also define function types that describe a function’s signature. The following code rewrites CalculateDiscount from my CustomerShort class to accept a single parameter called discountAmount: ...
If you try running TypeScript 5.1 under an older version of Node.js such as Node 10 or 12, you may see an error like the following from running either tsc.js or tsserver.js: Copy node_modules/typescript/lib/tsserver.js:2406 for (let i = startIndex ?? 0; i < array.length; i+...
functionsanitizeFoo(checker:any){if(typeofchecker.number!="number"||typeofchecker.boolean!="boolean"||(checker.maybeString!=undefined&&typeofchecker.maybeString!="string")||!sanitizeBar(checker.bar)){returnfalse;}returntrue;}functionsanitizeBar(checker:any){if(!sanitizenumberArray(checker.numbers)...
数组类型(Array) 代码语言:javascript 复制 constarr:number[]=[1,2,3];constarr1:Array<number>=[1,2,3]; 类(class) 代码语言:javascript 复制 classMan{name:string;constructor(name:string){this.name=name;}sayHi():void{console.log('Hi'+this.name);}}//使用new关键字来实例化类的对象varobj=ne...
TypeScript now assumes that you have made the necessary check. The type assertion says thatrandomValueshould be treated as astringand then thetoUpperCasemethod can be applied. Type guards The previous example demonstrates the use oftypeofin theifblock to examine the type of an expression at run...
TypeScript 包含各种基本类型，例如 Number、Array、Tuple、Boolean、String 等等。好吧，其中一些类型在 ...
function sum(nums: number[]): number: UseReadonlyArrayif a function does not write to its parameters. interface Foo { new(): Foo; }: This defines a type of objects that are new-able. You probably wantdeclare class Foo { constructor(); }. ...
if ("startDate" in emp) { console.log("Start Date: " + emp.startDate); } } 4.2 typeof 关键字 function padLeft(value: string, padding: string | number) { if (typeof padding === "number") { return Array(padding + 1).join(" ") + value; ...