type Test2=`names.${number}.firstName.lastName.${number}`;type SplitTemplateStringTypeToTuple<T>=Textends`${infer First}.${infer Rest}`// 此分支表示需要继续递归?Firstextends`${number}`?[number,...SplitTemplateStringType
console.log('third value is: ', pair[2]); // ❌ Error: Tuple type '[string, number]' of length '2' has no element at index '2'. console.log(pair[1].split('-')); // ❌ Error: Property 'split' does not exist on type 'number'. } 为什么说是一般呢,因为元组里可以有可选...
1、简单的例子let myFavoriteNumber: string | number;myFavoriteNumber = 'seven';myFavoriteNumber = 7;let myFavoriteNumber: string | number;myFavoriteNumber = true; // index.ts(2,1): error TS2322: Type 'boolean' is not assignable to type 'string | number'.// Type 'boolean' is not ass...
NAME:string; OS:string;// Unknown properties are covered by this index signature.[propName:string]:string; }declareconstenv: EnvironmentVars;// Declared as existingconstsysName= env.NAME;constos= env.OS;// Not declared, but because of the index// signature, then it is considered a stringco...
letstr3:string='Hi Tutlane'; console.log(str3.replace('Hi','Welcome to'));// Welcome to Tutlane // split() Method letstr4:string='Suresh, Rohini, Trishi'; console.log(str4.split(','));// [ 'Suresh', ' Rohini', ' Trishi' ] ...
//返回对象同时具有index和input属性,index为匹配到字符串的索引,input为进行匹配的字符串str 2、查询/搜索方法 //返回值为匹配字符的索引,如未查询到则返回-1 search() 方法用于检索字符串中指定的子字符串,或检索与正则表达式相匹配的子字符串。 3、替换方法,两个参数,用参数二替换参数一,参数一为字符串或正...
function handler (arg: string | null | undefined) { let str: string = arg!; // 没毛病 str.split(''); // ... } 1. 2. 3. 4. 5. 看下编译结果: "use strict"; function handler(arg) { let str = arg; str.split(''); ...
propertyKey: string | symbol - 方法名 parameterIndex: number - 方法中参数的索引值 functionLog(target:Function,key:string,parameterIndex:number){letfunctionLogged=key||target.prototype.constructor.name;console.log(`The parameter in position${parameterIndex}at${functionLogged}has been decorated`);}clas...
at index '2'. console.log(pair[1].split('-')); // ❌ Error: Property 'split' does...
let foo = 1;foo.split(' ');// Property 'split' does not exist on type 'number'.// 编译时会报错(数字没有 split 方法),无法通过编译 这段TypeScript 代码看上去和 JavaScript 没有什么区别。 实际上大部分 JavaScript 代码都只需要经过少量的修改(或者完全不用修改)就能变成 TypeScript 代码,这得益于...