(0));// 84// concat():concat(...strings: string[]): string;console.log(str.concat(' and concat.'));// This is string and concat.// indexOf():indexOf(searchString: string, position?: number): number;console.log(str.indexOf('i'));// 2// lastIndexOf():lastIndexOf(search...
functionadd(x:number|string, y:number|string){if(typeofx ==='number'&&typeofy ==='number') {returnx + y; }if(typeofx ==='string'&&typeofy ==='string') {returnx.concat(y); }thrownewError('Parameters must be numbers or strings'); }console.log(add('one','two'));/...
type Strings = [string, string]; type Numbers = number[]; type Unbounded = [...Strings, ...Numbers, boolean]; // [string, string, ...(number | boolean)[]] 结合使用这两种行为,我们能够为concat函数编写一个良好的类型签名: type Arr = readonly any[]; function concat<T extends Arr, ...
function concat(arr1: [], arr2: []): [];function concat<A>(arr1: [A], arr2: []): [A];function concat<A, B>(arr1: [A, B], arr2: []): [A, B];function concat<A, B, C>(arr1: [A, B, C], arr2: []): [A, B, C];function concat<A, B, C, D>(arr1: [...
主要接口是:String.concat(...strings: string[]): string支持参数输入一个或者多个字符串 // 示例1 let str1 = "Hello"; let str2 = " TypeScript"; let content = str1.concat(str2); console.log(content); // "Hello TypeScript" // 示例2: ...
s.concat("b")calls theconcatmethodon the string object. As in the 1stexercise in this sequence, the method creates a fresh string object for"ab"and returns it, but that return value is not assigned to anything, and the new object is discarded.Strings are immutable, so the existing string...
type Strings = [string, string]; type Numbers = number[]; type Unbounded = [...Strings, ...Numbers, boolean];By combining both of these behaviors together, we can write a single well-typed signature for concat:type Arr = readonly any[]; function concat<T extends Arr, U extends Arr>...
Template Strings Use .concat() Template strings in TypeScript previously just used the + operator when targeting ES3 or ES5; however, this leads to some divergences between the use of .valueOf() and .toString() which ends up being less spec-compliant. This is usually not noticeable, but ...
function concat<T, U>(arr1: T[], arr2, U[]): Array<T | U>; 在Typescript 4,可以在定义中对数组进行解构,通过几行代码优雅的解决可能要重载几百次的场景: 代码语言:javascript 复制 type Arr = readonly any[]; function concat<T extends Arr, U extends Arr>(arr1: T, arr2: U): [....
一个确定构造函数对象,是否识别一个对象为构造函数的实例之一的方法。由instanceof操作符的语义调用。5.2.2 Symbol.isConcatSpreadable一个布尔值,表示一个对象应该被Array.prototype.concat平铺到其数组元素。5.2.3 Symbol.iterator返回一个对象的默认迭代器的方法。被 for-of 语句的语义所调用。