parameterIndex: number - 方法中参数的索引值 function Log(target: Function, key: string, parameterIndex: number) { let functionLogged = key || target.prototype.constructor.name; console.log(`The parameter in position
class Derived extends Base { getName() { return "world"; }} const d = new Derived();d.printName();注意，如果我们忘记实现基类的抽象成员，我们会得到一个报错：class Derived extends Base {// Non-abstract class 'Derived' does not implement inherited abstract member 'getName' from class...
Class decorators Method decorators Field decorators Function parameter decorators Chop down if long With this option selected, decorators will be formatted as one per line if they go beyond the right margin. Wrap always With this option selected, all decorators will be formatted as one per...
log(name); // Output: John Doe const invalidProperty = getUserProperty(user, 'age'); // Error: Argument of type '"age"' is not assignable to parameter of type '"id" | "name" | "email"' 6.类型守卫 类型保护允许你根据特定条件,在条件块中缩小变量的类型范围。 代码语言:javascript 代码...
class Point { x = 0; y = 0; } const pt = new Point(); // Prints 0, 0 console.log(`${pt.x}, ${pt.y}`); 就像const、let和var一样,类属性的初始化器将用于推断其类型: const pt = new Point(); pt.x = "0"; //Type 'string' is not assignable to type 'number'. ...
parameterIndex: number - 方法中参数的索引值 functionLog(target:Function,key:string,parameterIndex:number){letfunctionLogged=key||target.prototype.constructor.name;console.log(`The parameter in position${parameterIndex}at${functionLogged}has been decorated`);}classGreeter{greeting:string;constructor(@Log...
TypeScript provides a convenient way to define class members in the constructor, by adding a visibility modifiers to the parameter. Example classPerson { // name is a private member variable publicconstructor(privatename: string) {} publicgetName(): string { ...
// Badclass Foo { Bar: number Baz(): number {}}// Goodclass Foo { bar: number baz(): number {}} 导入模块的命名空间时使用 camelCase 命名法。import * as fooBar from './foo_bar'不要为私有属性或方法名添加下划线 _ 前缀或后缀。尽可能使用完整的单词拼写命名，命名应当具有描述性且...
类型断言有两种形式,分别是尖括号语法和as 语法。这里说一下 as 语法:value as type。请看示例: let someValue: any ="this is a string"; let strLength: number= (someValueasstring).length; 上述示例改成这样,r 就不会报错了。 //告诉编译器,r 一定是一个 numberconstr = arr.find(item => item...
The following classes accept any type parameter: FindCursor AggregationCursor You can find a code snippet that shows how to specify a type for the FindCursor class in the Find Multiple Documents Usage Example. Limitations The driver cannot infer the type of values with keys containing dot notati...