module Admin { // use the export keyword in TypeScript to access the class outside export class Employee { constructor(name: string, email: string) { } } let alex = new Employee('alex', 'alex@gmail.com'); } // The Admin variable will allow you to access the Employee class outside...
'number' does not have 'substr'//当访问一个越界的元素,会使用联合类型替代:x[3] ='world';//OK, 字符串可以赋值给(string | number)类型console.log(x[5].toString());//OK, 'string' 和 'number' 都有 toStringx[6] =true;//Error, 布尔不是(string ...
module Admin { // use the export keyword in TypeScript to access the class outside export class Employee { constructor(name: string, email: string) { } } let alex = new Employee('alex', 'alex@gmail.com'); } // The Admin variable will allow you to access the Employee class outside...
interfaceAdmin{name:string;privileges:string[];}interfaceEmployee{name:string;startDate:Date;}type UnknownEmployee=Employee|Admin;functionprintEmployeeInformation(emp:UnknownEmployee){console.log("Name: "+emp.name);if("privileges"inemp){console.log("Privileges: "+emp.privileges);}if("startDate"inemp...
moduleAdmin {// use the export keyword in TypeScript to access the class outsideexportclassEmployee {constructor(name:string, email:string) { }}letalex =newEmployee('alex','alex@gmail.com');}// The Admin variable will allow you to access the Employee...
Type '[string, number, string]' is not assignable to type '[string, number]'. */ Any (任意值) any与类型系统中的任何类型都兼容。意味着可以将任何内容赋值给它,也可以将它赋值给任何类型。它能让你避开类型检查。 let variable: any = 'a string'; ...
// Code 1.2varisCompleted;// Assign nullisCompleted =null;console.log('When null:', isCompleted);// Re-assign a booleanisCompleted =false;console.log('When boolean:', isCompleted);// Re-assign a stringisCompleted ='Not Yet!';console.log('When string:', isCompleted);// Re-assign a...
asyncFactory: Function | void; // async component factory functionasyncMeta: Object | void;isAsyncPlaceholder: boolean;ssrContext: Object | void;fnContext: Component | void; // real context vm for functional nodesfnOptions: ?ComponentOptions; // for SSR cachingfnScopeId: ?string; // ...
TypeScript 5.2 now has a refactoring to inline the contents of a variable to all usage sites. A variable called 'path' initialized to a string, having both of its usages replaced, image. Using the "inline variable" refactoring will eliminate the variable and replace all the variable’s usage...
If you’re curious, you can quickly check this on the TypeScript Playground. For a string enum, we can produce a union type out of the literal types of its values, but it doesn’t happen the other way. Use cases and the importance of string-based enums String-based enums were only...