private 和 protected。 public: 默认的修饰符,它表示属性或方法是公有的,可以在类的内部和外部被访问。 private: 表示属性或方法是私有的,只能在类的内部被访问,外部无法访问。 protected: 表示属性或方法是受保护的,只能在类的内部及其子类中被访问,外部无法访问。 1.private 修饰符 示例: classPerson{privatenam...
// 字符串类型 let str: string = "yao"; // 数字类型 let num: number = 777; // 布尔类型 let flag: boolean = false; // 数组类型 在元素类型后面加上[] 或者使用数组泛型 let arr: number[] = [1,2,3]; let arr2: Array<number>= [1,2,3]; // 元祖 用来表示已知的数量和类型的...
使用常见配置选项 {"compilerOptions": {"target": "ES6", // 目标语言的版本"removeComments": true, // 删除注释"outDir": "./dist/", // 编译输出路径"sourceMap": true, // 生成目标文件的sourceMap文件},"files": [ // 指定待编译文件"./src/index.ts"]} 温馨提示 sourceMap 本质上是一个信息...
2] // 元组,数量和类型严格匹配 const array3: [number, string] = [1, '2'] // 对象声明 interface MyObject { name: string; age?: number; // 可选属性 readonly id: number; // 只读属性 update(val: string): void // 方法声明 update: (val: string) => void // 另一种方法声明 (...
"lib": ["DOM", "ES2015", "ScriptHost","ES2019.Array"], // TS需要引用的库,即声明文件,es5 默认引用dom、es5、scripthost,如需要使用es的高级版本特性,通常都需要配置,如es8的数组新特性需要引入"ES2019.Array", "allowJS": true, // 允许编译器编译JS,JSX文件 ...
类型有:number、string、boolean、字面量、any、unknown、void、never、object、array、tuple、enum 用法: let a:number = 20 1. 字面量 let n1:10 n1 = 10 # n1 = 20 报错 1. 2. 3. unknown类型和any类型 可以将任意类型的值赋值给unknown类型或any类型的变量; ...
Then we can add, update or delete entries from the Map using its inbuilt methods. myMap.set("Lokesh", 37); myMap.set("Raj", 35); //Get value by key let age = myMap.get("Lokesh"); // age = 37 //Check entry by Key myMap.has("Lokesh"); // true //Delete entry by key ...
Array.prototype.from, Promise, Map... is undefined?TypeScript or Babel only provides down-emits on syntactical features (class, let, async/await...), but not on functional features (Array.prototype.find, Set, Promise...), . For that, you need Polyfills, such as core-js or babel-...
Negated types (not, exclusion, exclude, remove):#4196 Exact types (sealed, final, closed, unopen):#12936 Behavior That Looks Wrong (And Arguably Is) But Is Currently Working As Intended Method and function signatures behave differently, specifically that narrower argument types are unsoundly allo...
operator should just "disappear" since the intent was to remove null and undefined from the type of bar. In other words, most people felt that the original snippet should be interpreted as foo?.bar.baz which just evaluates to undefined when foo is undefined. This is a breaking change, bu...