TypeScript

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声明数组的三种方式

  • let array1: string[] = ['name', 'age'];
  • let array2: Array<string> = ['name', 'age'];
  • let array3: [string] = ['name', 'age']; (推荐)
  • let array4: [string, number] = ['name', 123];

声明枚举


enum Color {
    Red,
    Green,
    Blue = 5
};
let color1: Color = Color.Green; // print 1
let color2: Color = Color.Blue; // print 5
let colorName: string = Color[0]; // print Red

声明联合类型


let foo: string | number = 123;
foo = 'foo'; // 合法
foo = true; // 不合法

类型断言


let someValue: any = "this is a string";
let strLength: number = (someValue).length;

或者:(推荐)


let someValue: any = "this is a string";
let strLength: number = (someValue as string).length;
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