indexOf(searchValue: string, startIndex?: number): number 返回第一个找到的指定字符串或字符的索引位置,可指定起始搜索位置。 代码语言:typescript 复制 letstr:string='Hello, World!';console.log(str.indexOf('o'));// 输出:4console.log(str.indexOf('o',5));// 输出:7 toUpperCase(): string...
index.less'; export interface BeforeUploadFunc { (file:File, fileList:FileList): boolean | Promise<File>; } export interface SuccessBack { (url: string): string; } export interface ChangeFunc { (value: string | Array<string>): void; } export interface IProps { action: string; listType?
name: string; age: number; } letpeople: Person[] = [ { name:"Alice", age: 20 }, { name:"Bob", age: 30 }, ]; 在这个例子中,Person[]是一个对象数组类型,它包含的元素都是Person类型的对象。每个Person类型的对象都有name和age两个属性,类型分别为string和number。 1.3、简单数组类型和泛型数...
[x: string]: string } 这样声明后,就不能声明number类型的成员了,会报错 interface stringIndex { [x: string]: string y: number;//Property 'y' of type 'number' is not assignable to string index type 'string'.} 3,两种索引签名混用: 在上边的字符串索引接口stringIndex中,添加数字索引签名 interf...
interfaceSomeType{/** This is an index signature. */[propName:string]:any;}functiondoStuff(value:SomeType){letx=value["someProperty"];} 在我们需要处理具有任意属性的对象的情况下,这会变得很麻烦。例如,假设一个API,在一个属性名末尾多打了一个s字符是很常见的拼写错误。
ts复制代码interfaceUser{name:stringage:numberaddress:string}functionupdateUser(user:User,fieldsToUpdate:Partial<User>){return{...user,...fieldsToUpdate}}constuser:User={name:'xiaoming',age:30,address:'上海'}constnewUser=updateUser(user,{address:'北京'}) ...
Back when TypeScript first introduced index signatures, you could only get properties declared by them with “bracketed” element access syntax likeperson["name"]. Copy interfaceSomeType{/** This is an index signature. */[propName:string]:any;}functiondoStuff(value:SomeType){letx=value["some...
TypeScript now more accurately checks whether or not strings are assignable to the placeholder slots of a template string type. Copy functiona<Textends{id:string}>() {letx:`-${keyof T &string}`;// Used to error, now doesn't.x ="-id"...
export type BasicPrimitive = number | string | boolean ; export function doStuff ( value : BasicPrimitive ) { let x = value ; return x ; } 我们可以将上面的代码粘贴到TS Playground中运行,然后将鼠标hover到变量上,发现ts会自动推断出x变量的类型,如下图所示: ...
declare module "libname" { // Types inside here export function helloWorldMessage(): string; } Test editing an existing package You can edit the types directly in node_modules/@types/foo/index.d.ts to validate your changes, then bring the changes to this repo with the steps below. Alternat...