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                ??碼云GVP開源項目 12k star Uniapp+ElementUI 功能強大 支持多語言、二開方便! 廣告
                # 1.基本類型 ``` // 基本類型,類型:小寫 let str: string = "hello";//字符串 let num: number = 123;//數字 let bool: boolean = true;//布爾 let any: any = "999";//任意類型 any = 123; let nu: null = null;//null let und: undefined = undefined;//underfined ``` # 2.數組類型 ``` // 數組類型: 1.每一項是固定類型 //數組每一項必須都為數字 // 寫法一: let arr1: number[] = [1, 2, 3]; //寫法二:Array:其實就是interface + 泛型:interface Array<T>{ } let arr2: Array<number> = [1, 2, 3]; let arr3: string[] = ['1', '2', '3'];//每一項必須為字符串 2.可能存在多類型 let arr4: [number, string] = [1, "1"];//第一項為數字,第二項為字符串,一對一約束 let arr5: (string | number)[] = [1, "2"];//數字或字符串,不是一對一,或的關系 ``` # 3.void ``` void類型:無返回值 //無返回值時: function fun(a: number, b: number): void { console.log(a + b); } //有返回值時: function fun1(a: number, b: number): number { return a + b; } ``` # 4.對象類型 ``` //一般寫法,實際不推薦,開發中一般用interface去定義 //屬性后面加 “ ? ”:意思是可有可無 let obj1: { name: string, age: number ,sex?:number} = { name: '張三', age: 15 } ``` # 5.給類型起別名 ``` //寫法:type 類型名稱(一般建議首字母大寫) = 類型 1.簡單類型 type Mystr = string;//定義 let str:Mystr = "hello";//使用自定義類型 2.復雜類型 type MyArr = (number | string) [];//定義復雜的數組類型 let arr: MyArr = [1,"2",3]; 3.函數類型注解 type Fn = (n1:number,n2:number) =>number ; const add1 : Fn = (a,b)=>{return a+b } ```
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