log("数字是正数"); }else if(num = 0){ console.log("数字是0"); }else{ console.log("数字是负数"); } } getNum(-1); TypeScript中的参数。 TypeScript中的参数分为正常参数,可选参数,剩余参数。 正常参数,方法在定义时需要几个参数就定义几个参数,调用时也需要上送对用的参数个数和参数类型。
if (checkGrammarTopLevelElementForRequiredDeclareModifier(decl)) { return true; } } } } 3.5.11. checkGrammarTopLevelElementForRequiredDeclareModifier function checkGrammarTopLevelElementForRequiredDeclareModifier(node: Node): boolean { if (node.kind === SyntaxKind.InterfaceDeclaration || node.kind =...
exactOptionalPropertyTypes设置可选属性不能赋值为undefined。 //打开 exactOptionalPropertyTypesinterfaceMyObj { foo?:'A'|'B'; } let obj:MyObj= { foo:'A'}; obj.foo= undefined;//报错 上面示例中,foo是可选属性,打开exactOptionalPropertyTypes以后,该属性就不能显式赋值为undefined。 16. forceConsiste...
functionbound(originalMethod:any,context:ClassMethodDecoratorContext){constmethodName=context.name;if(context.private){thrownewError(`'bound' cannot decorate private properties like${methodNameasstring}.`);}context.addInitializer(function(){this[methodName]=this[methodName].bind(this);});} bound不会...
typeCheckKey<T, Kextendskeyof T> = Kextends'name'?true:false;interfacePerson {name:string;age:number;}typeIsNameKey = CheckKey<Person,'name'>;// Result: truetypeIsCityKey = CheckKey<Person,'city'>;// Result: false 在此示例中,CheckK...
interface A { a: string; } interface B { b: string; } type MyType = A | B; function isA(x: MyType): x is A { return "a" in x; } function someFn(x: MyType) { if (isA(x) === true) { console.log(x.a); // works! } } We’d like to thank Mateusz Burzyński fo...
exportinterfaceFoo{number:number;boolean:boolean;maybeString?:string;bar:Bar;}interfaceBar{numbers:number[];} With strict mode functionsanitizeFoo(checker:any){if(typeofchecker.number!="number"||typeofchecker.boolean!="boolean"||(checker.maybeString!=undefined&&typeofchecker.maybeString!="string")...
interface Options { /** File patterns to be excluded. */ exclude?: string[]; /** * It handles any extra properties that we haven't declared as type 'any'. */ [x: string]: any; } function processOptions(opts: Options) { // Notice we're *intentionally* accessing `excludes`, not...
interface Person { name: string; age: number; } type IsNameKey = CheckKey<Person, 'name'>; // Result: true type IsCityKey = CheckKey<Person, 'city'>; // Result: false 在此示例中,CheckKey 是一个条件类型,用于检查提供的键是否为“name”。
接口是用关键字定义的interface,它可以包含使用函数或箭头函数的属性和方法声明。 interfaceIEmployee {empCode:number;empName:string;getSalary:(number) =>number;// arrow functiongetManagerName(number):string;} 6、TypeScript 中的模块是什么? TypeScript 中的模块是相...