What are the methods for defining and using arrays in T…

In TypeScript, the definition and usage of arrays are similar to JavaScript. Below are common methods for defining and using arrays.

1. Declare an array.

let arr: number[]; // 声明一个只能存储 number 类型的数组
let arr: Array<number>; // 使用泛型声明一个只能存储 number 类型的数组
let arr: any[]; // 声明一个可以存储任意类型的数组

1. Initialize an array:

let arr: number[] = [1, 2, 3]; // 初始化一个存储 number 类型的数组，并赋值
let arr: Array<number> = [1, 2, 3]; // 使用泛型初始化一个存储 number 类型的数组，并赋值
let arr: any[] = [1, 'two', true]; // 初始化一个可以存储任意类型的数组，并赋值

1. Accessing array elements.

let arr: number[] = [1, 2, 3];
console.log(arr[0]); // 输出 1
console.log(arr[1]); // 输出 2
console.log(arr[2]); // 输出 3

1. Length of array:

let arr: number[] = [1, 2, 3];
console.log(arr.length); // 输出 3

1. Traverse the array:

let arr: number[] = [1, 2, 3];
for (let i = 0; i < arr.length; i++) {
  console.log(arr[i]);
}

// 或者使用 forEach 方法
arr.forEach(element => {
  console.log(element);
});

1. Add elements to the array.

let arr: number[] = [1, 2, 3];
arr.push(4); // 添加元素到数组末尾
arr.unshift(0); // 添加元素到数组开头

1. Remove array elements.

let arr: number[] = [1, 2, 3];
arr.pop(); // 删除数组末尾的元素
arr.shift(); // 删除数组开头的元素

1. Merge arrays.

let arr1: number[] = [1, 2, 3];
let arr2: number[] = [4, 5, 6];
let arr3: number[] = arr1.concat(arr2); // 数组拼接
console.log(arr3); // 输出 [1, 2, 3, 4, 5, 6]

1. Slicing arrays:

let arr: number[] = [1, 2, 3, 4, 5];
let slicedArr: number[] = arr.slice(1, 4); // 返回一个新的数组，包含原数组中指定的开始和结束索引之间的元素
console.log(slicedArr); // 输出 [2, 3, 4]

The above are some common array definitions and usage methods, there are many other methods available in both TypeScript and JavaScript documentation that you can refer to.