for...of 语句创建一个循环来迭代可迭代的对象。在 ES6 中引入的 for...of 循环,以替代 for...in 和 forEach() ,并支持新的迭代协议。for...of 允许你遍历 Arrays(数组), Strings(字符串), Maps(映射), Sets(集合)等可迭代的数据结构等。 TypeScript for...of 循环
2.Compute a string value by concatenating the three strings “[object “, Result (1), and “]”. 3.Return Result (2) 上面的规范定义了Object.prototype.toString的行为:首先,取得对象的一个内部属性[[Class]],然后依据这个属性,返回一个类似于”[object Array]”的字符串作为结果(看过ECMA标准的应该...
Splits a String object into an array of strings by separating the string into substrings. 12. substr() Returns the characters in a string beginning at the specified location through the specified number of characters. 13. substring() Returns the characters in a string between two indexes in...
// 字符串数组 let strings: string[] = ['1','2','3'] // 还有一种不常用的写法 let numbers2: Array<number> = [1,2,3] 1. 2. 3. 4. 5. 6. 7. 联合类型 // 数组中既有number类型,又有string类型 let arr: (number | string)[] = [1,'2'] // 注意如果不添加小括号,代表既可...
Arrays can contain elements of any data type, numbers, strings, or even objects. Arrays can be declared and initialized separately. Example: Array Declaration and Initialization Copy let fruits: Array<string>; fruits = ['Apple', 'Orange', 'Banana']; let ids: Array<number>; ids = [23,...
上面例子里,我们定义了StringArray接口,它具有索引签名。 这个索引签名表示了当用number去索引StringArray时会得到string类型的返回值。 Typescript支持两种索引签名:字符串和数字。 可以同时使用两种类型的索引,但是数字索引的返回值必须是字符串索引返回值类型的子类型。
string, ...Array<number | boolean>]type Unbounded = [...Strings, ...Numbers, boolean];通过将这两种功能结合在一起，就可以很便捷的编写一个类型正确的签名concat：type Arr = readonly any[];function concat<T extends Arr, U extends Arr>(arr1: T, arr2: U): [...T, ...U] { return...
:string]=["hello"];d=["hello","world"];// A tuple with a *rest element* - holds at least 2 strings at the front,// and any number of booleans at the back.lete:[string,string,...boolean[]];e=["hello","world"];e=["hello","world",false];e=["hello","world",true,false...
允许你遍历 Arrays(数组), Strings(字符串), Maps(映射), Sets(集合)等可迭代的数据结构等 let someArray = [1,"string",false];for(let entry of someArray) { console.log(entry);//1, "string", false} while 一般用于未知循环次数 varnum =5;varfactorial =1;while(num >=1) { ...
1.Array.slice()Syntax Theslice()method takes two optional parameters:startandend. By default thestartis0andendisarray.length. Syntax Array.slice(start?:number|undefined,end?:number|undefined): start(inclusive): The beginning index of the array. ...