let colors: string[] = ["red", "green", "blue"]; for(let i in colors) { console.log(i); } TypeScript Object 对象解构 代码语言:javascript 代码运行次数:0 运行 AI代码解释 let person = { name: 'Semlinker', gender: 'male' }; let {name, gender} = person; 对象展开运算符 代码语言...
functionprintName(obj:{first:string;last?:string}){// 如果 obj.last 没有对应的值,可能会报错!console.log(obj.last.toUpperCase());// Object is possibly 'undefined'.if(obj.last!==undefined){// OKconsole.log(obj.last.toUpperCase());}// 下面是使用现代 JavaScript 语法的另一种安全写法:consol...
An interface can have multiple merged declarations, but a type alias for an object type literal cannot. 相同点 两者都可以描述一个对象或者函数; 都支持拓展(extends),语法不一样; type TBasicInfo = { name: string; } type TUser = TBasicInfo & { religion: string }; interface IUser extends ...
console.log(typeofnum1);//numberconsole.log(typeofstr1,);//stringconsole.log(typeofisTrue);//booleanconsole.log(typeofundefinedVar);//undefinedconsole.log(typeofnullVar);//objectconsole.log(typeofsymbol1);//symbolconsole.log(typeofbigIntNum);//bigintconsole.log(typeofnotANumber);//number...
<Child2 name={name} />TypeScript</Child1>); }; exportdefaultApp; Child1组件结构如下: interface IProps { name: string; } const Child1: React.FC<IProps> = (props) =>{ const { name, children }=props; console.log(children);return(<div className="App"> ...
interface A { name: string age: number } let a: A = { name: '张三', age: 18, salary: '20K' // TS2322: Type '{ name: string; age: number; salary: string; }' is not assignable to type 'A'. // Object literal may only specify known properties, and 'salary' does not exist...
interfacePerson{readonlyname:string;age: number;}constjohn: Readonly<Person> = { name:'John', age:30};john.age =31;// Error: Cannot assign to 'age' because it is a read-only property. 在此示例中,age 属性可以修改,但 name 属性是只...
什么是?和Optional Properties呢?interface的某些非required属性名的末尾,添加?这是一个optional property,其实就是字面意思,条件属性。 Optional Property只是属性名,也就是options?: ?Object,中options后的问号,拿属性值类型前的问号是什么意思,也就是?Object,是什么意思?
}returnnames.map(name => {url.searchParams.set("name", name)// ~~~// error!// Property 'searchParams' does not exist on type 'string | URL'.returnurl.toString(); }); } Here, TypeScript decided that it wasn’t "safe" to assume thaturlwasactuallyaURLobject in our callback functi...
Uncapitalize<StringType>:将字符串首字母转为小写格式 type UppercaseGreeting = "HELLO WORLD"; type UncomfortableGreeting = Uncapitalize<UppercaseGreeting>; // 相当于 type UncomfortableGreeting = "hELLO WORLD" typescript 本文系转载,阅读原文 https://zhuanlan.zhihu.com/p/640499290 ...