array.md

# Array

Array 对象是用于构造数组的全局对象，数组是类似于列表的高阶对象。

## 构造函数

### new \<T>(...items : T\[]) : T[]@Constructor(...items)

<!-- UTSJSON.Array.Constructor.description -->

<!-- UTSJSON.Array.Constructor.param -->

<!-- UTSJSON.Array.Constructor.returnValue -->

<!-- UTSJSON.Array.Constructor.test -->

<!-- UTSJSON.Array.Constructor.compatibility -->

<!-- UTSJSON.Array.Constructor.tutorial -->

::: warning 注意事项

与JS中的`Array` 不同，`UTS`不支持的指定长度初始化Array的写法

```ts
let arr = new Array(10)
```

上面的代码在不同的平台的表现有差异:

- web平台

	一个长度为10的数组，每一个元素都是 undefined

- Android/ios平台

	一个长度为1的数组，其元素为 数字10

:::


## 实例属性

### length

<!-- UTSJSON.Array.length.description -->

<!-- UTSJSON.Array.length.param -->

<!-- UTSJSON.Array.length.returnValue -->

<!-- UTSJSON.Array.length.test -->

<!-- UTSJSON.Array.length.compatibility -->

边界情况说明：

- 在不同平台上，数组的长度限制不同，超出限制会导致相应的错误或异常
  * 编译至 JavaScript 平台时，最大长度为 2^32 - 1，超出限制会报错：`Invalid array length`。
  * 编译至 Kotlin 平台时，最大长度受系统内存的限制，超出限制报错：`java.lang.OutOfMemoryError: Failed to allocate a allocation until OOM`。
  * 编译至 Swift 平台时，最大长度也受系统内存的限制，目前超出限制没有返回信息。


## 实例方法

### toString()

<!-- UTSJSON.Array.toString.description -->

<!-- UTSJSON.Array.toString.param -->

<!-- UTSJSON.Array.toString.returnValue -->

<!-- UTSJSON.Array.toString.test -->

<!-- UTSJSON.Array.toString.compatibility -->

<!-- UTSJSON.Array.toString.tutorial -->

### add(item)

<!-- UTSJSON.Array.add.description -->

<!-- UTSJSON.Array.add.param -->

<!-- UTSJSON.Array.add.returnValue -->

<!-- UTSJSON.Array.add.test -->

<!-- UTSJSON.Array.add.compatibility -->

<!-- UTSJSON.Array.add.tutorial -->

### toLocaleString()

<!-- UTSJSON.Array.toLocaleString.description -->

<!-- UTSJSON.Array.toLocaleString.param -->

<!-- UTSJSON.Array.toLocaleString.returnValue -->

<!-- UTSJSON.Array.toLocaleString.test -->

<!-- UTSJSON.Array.toLocaleString.compatibility -->

<!-- UTSJSON.Array.toLocaleString.tutorial -->

### joinToString(separator)

<!-- UTSJSON.Array.joinToString.description -->

<!-- UTSJSON.Array.joinToString.param -->

<!-- UTSJSON.Array.joinToString.returnValue -->

<!-- UTSJSON.Array.joinToString.test -->

<!-- UTSJSON.Array.joinToString.compatibility -->

<!-- UTSJSON.Array.joinToString.tutorial -->

### find(predicate, thisArg?)

<!-- UTSJSON.Array.find.description -->

<!-- UTSJSON.Array.find.param -->

<!-- UTSJSON.Array.find.returnValue -->

<!-- UTSJSON.Array.find.test -->

<!-- UTSJSON.Array.find.compatibility -->

### find(predicate, thisArg?)

<!-- UTSJSON.Array.find_1.description -->

<!-- UTSJSON.Array.find_1.param -->

<!-- UTSJSON.Array.find_1.returnValue -->

<!-- UTSJSON.Array.find_1.test -->

<!-- UTSJSON.Array.find_1.compatibility -->

<!-- UTSJSON.Array.find_1.tutorial -->

### find(predicate, thisArg?)

<!-- UTSJSON.Array.find_2.description -->

<!-- UTSJSON.Array.find_2.param -->

<!-- UTSJSON.Array.find_2.returnValue -->

<!-- UTSJSON.Array.find_2.test -->

<!-- UTSJSON.Array.find_2.compatibility -->

<!-- UTSJSON.Array.find_2.tutorial -->

### findIndex(predicate, thisArg?)

<!-- UTSJSON.Array.findIndex.description -->

<!-- UTSJSON.Array.findIndex.param -->

<!-- UTSJSON.Array.findIndex.returnValue -->

<!-- UTSJSON.Array.findIndex.test -->

<!-- UTSJSON.Array.findIndex.compatibility -->

### findIndex(predicate, thisArg?)

<!-- UTSJSON.Array.findIndex_1.description -->

<!-- UTSJSON.Array.findIndex_1.param -->

<!-- UTSJSON.Array.findIndex_1.returnValue -->

<!-- UTSJSON.Array.findIndex_1.test -->

<!-- UTSJSON.Array.findIndex_1.compatibility -->

<!-- UTSJSON.Array.findIndex_1.tutorial -->

### findIndex(predicate, thisArg?)

<!-- UTSJSON.Array.findIndex_2.description -->

<!-- UTSJSON.Array.findIndex_2.param -->

<!-- UTSJSON.Array.findIndex_2.returnValue -->

<!-- UTSJSON.Array.findIndex_2.test -->

<!-- UTSJSON.Array.findIndex_2.compatibility -->

<!-- UTSJSON.Array.findIndex_2.tutorial -->

### fill(value, start?, end?)

<!-- UTSJSON.Array.fill.description -->

<!-- UTSJSON.Array.fill.param -->

<!-- UTSJSON.Array.fill.returnValue -->

<!-- UTSJSON.Array.fill.test -->

需要注意的是，截止HBuilder 4.22  部分平台尚不支持[根据元素个数构造`Array`的写法](https://doc.dcloud.net.cn/uni-app-x/uts/buildin-object-api/array.html#constructor)

所以下面的代码在 部分平台可能不符合预期


```ts
new Array(20).fill(0)
```

可以使用下面的代码替代

```ts
let b = Array<Number>()
for(let i = 0; i < 20; i++){
  b.add(0)
}
```

<!-- UTSJSON.Array.fill.compatibility -->

### copyWithin(target, start?, end?)

<!-- UTSJSON.Array.copyWithin.description -->

<!-- UTSJSON.Array.copyWithin.param -->

<!-- UTSJSON.Array.copyWithin.returnValue -->

<!-- UTSJSON.Array.copyWithin.test -->

<!-- UTSJSON.Array.copyWithin.compatibility -->

### pop()

<!-- UTSJSON.Array.pop.description -->

<!-- UTSJSON.Array.pop.param -->

<!-- UTSJSON.Array.pop.returnValue -->

<!-- UTSJSON.Array.pop.test -->

<!-- UTSJSON.Array.pop.compatibility -->

### push(...items)

<!-- UTSJSON.Array.push.description -->

<!-- UTSJSON.Array.push.param -->

<!-- UTSJSON.Array.push.returnValue -->

<!-- UTSJSON.Array.push.test -->

<!-- UTSJSON.Array.push.compatibility -->

### concat(...items)

<!-- UTSJSON.Array.concat.description -->

<!-- UTSJSON.Array.concat.param -->

<!-- UTSJSON.Array.concat.returnValue -->

<!-- UTSJSON.Array.concat.test -->

<!-- UTSJSON.Array.concat.compatibility -->

### concat(...items)

<!-- UTSJSON.Array.concat_1.description -->

<!-- UTSJSON.Array.concat_1.param -->

<!-- UTSJSON.Array.concat_1.returnValue -->

<!-- UTSJSON.Array.concat_1.test -->

<!-- UTSJSON.Array.concat_1.compatibility -->

### join(separator?)

<!-- UTSJSON.Array.join.description -->

<!-- UTSJSON.Array.join.param -->

<!-- UTSJSON.Array.join.returnValue -->

<!-- UTSJSON.Array.concat_1.test -->

<!-- UTSJSON.Array.join.compatibility -->

### reverse()

<!-- UTSJSON.Array.reverse.description -->

<!-- UTSJSON.Array.reverse.param -->

<!-- UTSJSON.Array.reverse.returnValue -->

<!-- UTSJSON.Array.reverse.compatibility -->

### shift()

<!-- UTSJSON.Array.shift.description -->

<!-- UTSJSON.Array.shift.param -->

<!-- UTSJSON.Array.shift.returnValue -->

<!-- UTSJSON.Array.concat_1.test -->

<!-- UTSJSON.Array.shift.compatibility -->

### slice(start?, end?)

<!-- UTSJSON.Array.slice.description -->

<!-- UTSJSON.Array.slice.param -->

<!-- UTSJSON.Array.slice.returnValue -->

<!-- UTSJSON.Array.slice.test -->

<!-- UTSJSON.Array.slice.compatibility -->

### sort(compareFn?)

<!-- UTSJSON.Array.sort.description -->

<!-- UTSJSON.Array.sort.param -->

<!-- UTSJSON.Array.sort.returnValue -->

<!-- UTSJSON.Array.sort.test -->

<!-- UTSJSON.Array.sort.compatibility -->

**平台差异性**

在android平台，一定不能忽略两个对比元素相等的场景，否则可能会出现`java.lang.IllegalArgumentException: Comparison method violates its general contract!‌`
```

a.sort((a, b) : number => {
  // 这里的判断不能省略
  if(a.compareTo(b) == 0){
    return 0
  }
  return a - b
})
```



### splice(start, deleteCount, ...items)

<!-- UTSJSON.Array.splice.description -->

<!-- UTSJSON.Array.splice.param -->

<!-- UTSJSON.Array.splice.returnValue -->

<!-- UTSJSON.Array.splice.test -->

<!-- UTSJSON.Array.splice.compatibility -->

### unshift(...items)

<!-- UTSJSON.Array.unshift.description -->

<!-- UTSJSON.Array.unshift.param -->

<!-- UTSJSON.Array.unshift.returnValue -->

```ts
const array1 = [1, 2, 3];

console.log(array1.unshift(4, 5));
// expected output: 5

console.log(array1);
// expected output: Array [4, 5, 1, 2, 3]
```

<!-- UTSJSON.Array.unshift.compatibility -->

### indexOf(searchElement, fromIndex?)

<!-- UTSJSON.Array.indexOf.description -->

<!-- UTSJSON.Array.indexOf.param -->

<!-- UTSJSON.Array.indexOf.returnValue -->

```ts
const beasts = ['ant', 'bison', 'camel', 'duck', 'bison'];

console.log(beasts.indexOf('bison'));
// expected output: 1

// start from index 2
console.log(beasts.indexOf('bison', 2));
// expected output: 4

console.log(beasts.indexOf('giraffe'));
// expected output: -1

```

<!-- UTSJSON.Array.indexOf.compatibility -->

### lastIndexOf(searchElement, fromIndex?)

<!-- UTSJSON.Array.lastIndexOf.description -->

<!-- UTSJSON.Array.lastIndexOf.param -->

<!-- UTSJSON.Array.lastIndexOf.returnValue -->

```ts
const animals = ['Dodo', 'Tiger', 'Penguin', 'Dodo'];

console.log(animals.lastIndexOf('Dodo'));
// expected output: 3

console.log(animals.lastIndexOf('Tiger'));
// expected output: 1
```

<!-- UTSJSON.Array.lastIndexOf.compatibility -->

### every(predicate, thisArg?)

<!-- UTSJSON.Array.every.description -->

<!-- UTSJSON.Array.every.param -->

<!-- UTSJSON.Array.every.returnValue -->

```ts
const isBelowThreshold = (currentValue:number):boolean => currentValue < 40;
const array1 = [1, 30, 39, 29, 10, 13];
console.log(array1.every(isBelowThreshold));
// expected output: true
```

<!-- UTSJSON.Array.every.compatibility -->

### every(predicate, thisArg?)

<!-- UTSJSON.Array.every_1.description -->

<!-- UTSJSON.Array.every_1.param -->

<!-- UTSJSON.Array.every_1.returnValue -->

<!-- UTSJSON.Array.every_1.test -->

<!-- UTSJSON.Array.every_1.compatibility -->

<!-- UTSJSON.Array.every_1.tutorial -->

### every(predicate, thisArg?)

<!-- UTSJSON.Array.every_2.description -->

<!-- UTSJSON.Array.every_2.param -->

<!-- UTSJSON.Array.every_2.returnValue -->

<!-- UTSJSON.Array.every_2.test -->

<!-- UTSJSON.Array.every_2.compatibility -->

<!-- UTSJSON.Array.every_2.tutorial -->

### every(predicate, thisArg?)

<!-- UTSJSON.Array.every_3.description -->

<!-- UTSJSON.Array.every_3.param -->

<!-- UTSJSON.Array.every_3.returnValue -->

<!-- UTSJSON.Array.every_3.test -->

<!-- UTSJSON.Array.every_3.compatibility -->

<!-- UTSJSON.Array.every_3.tutorial -->


### some(predicate, thisArg?)

<!-- UTSJSON.Array.some.description -->

<!-- UTSJSON.Array.some.param -->

<!-- UTSJSON.Array.some.returnValue -->


```ts
const array = [1, 2, 3, 4, 5];

// checks whether an element is even
const even = (element:number):boolean=> element % 2 == 0;

console.log(array.some(even));
// expected output: true
```

<!-- UTSJSON.Array.some.compatibility -->

### some(predicate, thisArg?)

<!-- UTSJSON.Array.some_1.description -->

<!-- UTSJSON.Array.some_1.param -->

<!-- UTSJSON.Array.some_1.returnValue -->

<!-- UTSJSON.Array.some_1.test -->

<!-- UTSJSON.Array.some_1.compatibility -->

<!-- UTSJSON.Array.some_1.tutorial -->

### some(predicate, thisArg?)

<!-- UTSJSON.Array.some_2.description -->

<!-- UTSJSON.Array.some_2.param -->

<!-- UTSJSON.Array.some_2.returnValue -->

<!-- UTSJSON.Array.some_2.test -->

<!-- UTSJSON.Array.some_2.compatibility -->

<!-- UTSJSON.Array.some_2.tutorial -->

### forEach(callbackfn, thisArg?)

<!-- UTSJSON.Array.forEach.description -->

<!-- UTSJSON.Array.forEach.param -->

<!-- UTSJSON.Array.forEach.returnValue -->

```ts
const array1 = ['a', 'b', 'c'];
array1.forEach(element => console.log(element));
// expected output: "a"
// expected output: "b"
// expected output: "c"
```

> 特别注意：
> 不可在 forEach 的 callbackFn 里添加或者删除原数组元素，此行为是危险的，在 Android 平台会造成闪退，在 iOS 平台会造成行为不符合预期。如果想实现该效果，请用 while 循环。

```ts

const array1 = ['a', 'b', 'c'];
array1.forEach(element => {
	console.log(element)
	array1.pop() // 此行为在 Android 平台会造成闪退，在 iOS 平台会输出 'a', 'b', 'c', 而 JS 会输出 'a', 'b'
});

// 如果想让上述行为正常运行，可以用 while 循环实现：

let array1 = ['a', 'b', 'c'];
let index = 0;
while (index < array1.length) {
  console.log(array1[index]);
  array1.pop();
  index += 1;
}

```

<!-- UTSJSON.Array.forEach.compatibility -->

### forEach(callbackfn, thisArg?)

<!-- UTSJSON.Array.forEach_1.description -->

<!-- UTSJSON.Array.forEach_1.param -->

<!-- UTSJSON.Array.forEach_1.returnValue -->

<!-- UTSJSON.Array.forEach_1.test -->

<!-- UTSJSON.Array.forEach_1.compatibility -->

<!-- UTSJSON.Array.forEach_1.tutorial -->

### forEach(callbackfn, thisArg?)

<!-- UTSJSON.Array.forEach_2.description -->

<!-- UTSJSON.Array.forEach_2.param -->

<!-- UTSJSON.Array.forEach_2.returnValue -->

<!-- UTSJSON.Array.forEach_2.test -->

<!-- UTSJSON.Array.forEach_2.compatibility -->

<!-- UTSJSON.Array.forEach_2.tutorial -->

### map(callbackfn, thisArg?)

<!-- UTSJSON.Array.map.description -->

<!-- UTSJSON.Array.map.param -->

<!-- UTSJSON.Array.map.returnValue -->

```ts
const array1 = [1, 4, 9, 16];

// pass a function to map
const map1 = array1.map((x:number):number => x * 2);

console.log(map1);
// expected output: Array [2, 8, 18, 32]

```

<!-- UTSJSON.Array.map.compatibility -->

### map(callbackfn, thisArg?)

<!-- UTSJSON.Array.map_1.description -->

<!-- UTSJSON.Array.map_1.param -->

<!-- UTSJSON.Array.map_1.returnValue -->

<!-- UTSJSON.Array.map_1.test -->

<!-- UTSJSON.Array.map_1.compatibility -->

<!-- UTSJSON.Array.map_1.tutorial -->

### map(callbackfn, thisArg?)

<!-- UTSJSON.Array.map_2.description -->

<!-- UTSJSON.Array.map_2.param -->

<!-- UTSJSON.Array.map_2.returnValue -->

<!-- UTSJSON.Array.map_2.test -->

<!-- UTSJSON.Array.map_2.compatibility -->

<!-- UTSJSON.Array.map_2.tutorial -->

### filter(predicate, thisArg?)

<!-- UTSJSON.Array.filter.description -->

<!-- UTSJSON.Array.filter.param -->

<!-- UTSJSON.Array.filter.returnValue -->

```ts
const words = ['spray', 'limit', 'elite', 'exuberant', 'destruction', 'present'];

const result = words.filter((word:string):boolean => word.length > 6);

console.log(result);
// expected output: Array ["exuberant", "destruction", "present"]

```

<!-- UTSJSON.Array.filter.compatibility -->

### filter(predicate, thisArg?)

<!-- UTSJSON.Array.filter_1.description -->

<!-- UTSJSON.Array.filter_1.param -->

<!-- UTSJSON.Array.filter_1.returnValue -->

<!-- UTSJSON.Array.filter_1.test -->

<!-- UTSJSON.Array.filter_1.compatibility -->

<!-- UTSJSON.Array.filter_1.tutorial -->

### filter(predicate, thisArg?)

<!-- UTSJSON.Array.filter_2.description -->

<!-- UTSJSON.Array.filter_2.param -->

<!-- UTSJSON.Array.filter_2.returnValue -->

<!-- UTSJSON.Array.filter_2.test -->

<!-- UTSJSON.Array.filter_2.compatibility -->

<!-- UTSJSON.Array.filter_2.tutorial -->

### filter(predicate, thisArg?)

<!-- UTSJSON.Array.filter_3.description -->

<!-- UTSJSON.Array.filter_3.param -->

<!-- UTSJSON.Array.filter_3.returnValue -->

<!-- UTSJSON.Array.filter_3.test -->

<!-- UTSJSON.Array.filter_3.compatibility -->

<!-- UTSJSON.Array.filter_3.tutorial -->

### reduce(callbackfn)

<!-- UTSJSON.Array.reduce.description -->

<!-- UTSJSON.Array.reduce.param -->

<!-- UTSJSON.Array.reduce.returnValue -->

```ts
const array1 = [1, 2, 3, 4];

// 0 + 1 + 2 + 3 + 4
const initialValue = 0;
const sumWithInitial = array1.reduce(
  (previousValue:number, currentValue:number):number => previousValue + currentValue,
  initialValue
);

console.log(sumWithInitial);
// expected output: 10

```

<!-- UTSJSON.Array.reduce.compatibility -->


### reduce(callbackfn)

<!-- UTSJSON.Array.reduce_1.description -->

<!-- UTSJSON.Array.reduce_1.param -->

<!-- UTSJSON.Array.reduce_1.returnValue -->

<!-- UTSJSON.Array.reduce_1.test -->

<!-- UTSJSON.Array.reduce_1.compatibility -->

<!-- UTSJSON.Array.reduce_1.tutorial -->

### reduce(callbackfn, initialValue)

<!-- UTSJSON.Array.reduce_2.description -->

<!-- UTSJSON.Array.reduce_2.param -->

<!-- UTSJSON.Array.reduce_2.returnValue -->

<!-- UTSJSON.Array.reduce_2.test -->

<!-- UTSJSON.Array.reduce_2.compatibility -->

<!-- UTSJSON.Array.reduce_2.tutorial -->

### reduce(callbackfn, initialValue)

<!-- UTSJSON.Array.reduce_3.description -->

<!-- UTSJSON.Array.reduce_3.param -->

<!-- UTSJSON.Array.reduce_3.returnValue -->

<!-- UTSJSON.Array.reduce_3.test -->

<!-- UTSJSON.Array.reduce_3.compatibility -->

<!-- UTSJSON.Array.reduce_3.tutorial -->

### reduce(callbackfn, initialValue)

<!-- UTSJSON.Array.reduce_4.description -->

<!-- UTSJSON.Array.reduce_4.param -->

<!-- UTSJSON.Array.reduce_4.returnValue -->

<!-- UTSJSON.Array.reduce_4.test -->

<!-- UTSJSON.Array.reduce_4.compatibility -->

<!-- UTSJSON.Array.reduce_4.tutorial -->

### reduce(callbackfn, initialValue)

<!-- UTSJSON.Array.reduce_5.description -->

<!-- UTSJSON.Array.reduce_5.param -->

<!-- UTSJSON.Array.reduce_5.returnValue -->

<!-- UTSJSON.Array.reduce_5.test -->

<!-- UTSJSON.Array.reduce_5.compatibility -->

<!-- UTSJSON.Array.reduce_5.tutorial -->

### reduceRight(callbackfn)

<!-- UTSJSON.Array.reduceRight.description -->

<!-- UTSJSON.Array.reduceRight.param -->

<!-- UTSJSON.Array.reduceRight.returnValue -->

<!-- UTSJSON.Array.reduceRight.compatibility -->

### reduceRight(callbackfn)

<!-- UTSJSON.Array.reduceRight_1.description -->

<!-- UTSJSON.Array.reduceRight_1.param -->

<!-- UTSJSON.Array.reduceRight_1.returnValue -->

<!-- UTSJSON.Array.reduceRight_1.test -->

<!-- UTSJSON.Array.reduceRight_1.compatibility -->

<!-- UTSJSON.Array.reduceRight_1.tutorial -->

### reduceRight(callbackfn)

<!-- UTSJSON.Array.reduceRight_2.description -->

<!-- UTSJSON.Array.reduceRight_2.param -->

<!-- UTSJSON.Array.reduceRight_2.returnValue -->

<!-- UTSJSON.Array.reduceRight_2.test -->

<!-- UTSJSON.Array.reduceRight_2.compatibility -->

<!-- UTSJSON.Array.reduceRight_2.tutorial -->

### reduceRight(callbackfn, initialValue)

<!-- UTSJSON.Array.reduceRight_3.description -->

<!-- UTSJSON.Array.reduceRight_3.param -->

<!-- UTSJSON.Array.reduceRight_3.returnValue -->

<!-- UTSJSON.Array.reduceRight_3.test -->

<!-- UTSJSON.Array.reduceRight_3.compatibility -->

<!-- UTSJSON.Array.reduceRight_3.tutorial -->

### reduceRight(callbackfn, initialValue)

<!-- UTSJSON.Array.reduceRight_4.description -->

<!-- UTSJSON.Array.reduceRight_4.param -->

<!-- UTSJSON.Array.reduceRight_4.returnValue -->

<!-- UTSJSON.Array.reduceRight_4.test -->

<!-- UTSJSON.Array.reduceRight_4.compatibility -->

<!-- UTSJSON.Array.reduceRight_4.tutorial -->

### reduceRight(callbackfn, initialValue)

<!-- UTSJSON.Array.reduceRight_5.description -->

<!-- UTSJSON.Array.reduceRight_5.param -->

<!-- UTSJSON.Array.reduceRight_5.returnValue -->

<!-- UTSJSON.Array.reduceRight_5.test -->

<!-- UTSJSON.Array.reduceRight_5.compatibility -->

<!-- UTSJSON.Array.reduceRight_5.tutorial -->

### reduceRight(callbackfn, initialValue)

<!-- UTSJSON.Array.reduceRight_6.description -->

<!-- UTSJSON.Array.reduceRight_6.param -->

<!-- UTSJSON.Array.reduceRight_6.returnValue -->

<!-- UTSJSON.Array.reduceRight_6.test -->

<!-- UTSJSON.Array.reduceRight_6.compatibility -->

<!-- UTSJSON.Array.reduceRight_6.tutorial -->

### isArray(arg)

<!-- UTSJSON.Array.isArray.description -->

<!-- UTSJSON.Array.isArray.param -->

<!-- UTSJSON.Array.isArray.returnValue -->

```ts
console.log(Array.isArray([1, 3, 5]));
// Expected output: true

console.log(Array.isArray('[]'));
// Expected output: false

console.log(Array.isArray(new Array(5)));
// Expected output: true

console.log(Array.isArray(new Int16Array([15, 33])));
// Expected output: false
```

<!-- UTSJSON.Array.isArray.compatibility -->

### includes(searchElement, fromIndex?)

<!-- UTSJSON.Array.includes.description -->

<!-- UTSJSON.Array.includes.param -->

<!-- UTSJSON.Array.includes.returnValue -->

<!-- UTSJSON.Array.includes.compatibility -->

### toKotlinList()

<!-- UTSJSON.Array.toKotlinList.description -->

<!-- UTSJSON.Array.toKotlinList.param -->

<!-- UTSJSON.Array.toKotlinList.returnValue -->

<!-- UTSJSON.Array.toKotlinList.compatibility -->

<!-- UTSJSON.Array.toKotlinList.tutorial -->

<!-- UTSJSON.Array.tutorial -->



## Android 平台方法

* 目前 Array 类型编译到 `kotlin` 为 `io.dcloud.uts.UTSArray`, 该类继承自 `java.util.ArrayList`,所有`java` /`kotlin` 为其提供的扩展函数(如:`toTypedArray` 等)，均可以正常调用。


::: preview

> UTS

```ts
let utsArray = ["1",2,3.0]
// UTSArray 分别转换为 Java Array / Kotlin Array
let javaArray = utsArray.toTypedArray();
let kotlinArray = utsArray.toKotlinList()
// 从Java Array 转换为 UTSArray
let convertArrayFromJava = Array.fromNative(javaArray);
// 从Kotlin Array 转换为 UTSArray
let convertArrayFromKotlin = Array.fromNative(kotlinArray);
```

> Kotlin

```kotlin
val utsArray = utsArrayOf("1",2,3.0)
// UTSArray 分别转换为 Java Array / Kotlin Array
val javaArray = utsArray.toTypedArray();
val kotlinArray = utsArray.toKotlinList()
// 从Java Array 转换为 UTSArray
val convertArrayFromJava = UTSArray.fromNative(javaArray);
// 从Kotlin Array 转换为 UTSArray
val convertArrayFromKotlin = UTSArray.fromNative(kotlinArray);
```

:::


更多平台专属Array 参考[文档](https://doc.dcloud.net.cn/uni-app-x/uts/data-type.html#kotlin%E4%B8%93%E6%9C%89%E6%95%B0%E7%BB%84%E7%B1%BB%E5%9E%8B)

## 常见操作

- 创建数组
```ts
const fruits = ['Apple', 'Banana']
console.log(fruits.length)
```
- 通过索引访问数组元素
```ts
const first = fruits[0]
// Apple
const last = fruits[fruits.length - 1]
// Banana
```
- 遍历数组
```ts
fruits.forEach(function(item, index, array) {
  console.log(item, index)
})
// Apple 0
// Banana 1
```
- 注意：数组遍历不推荐使用 for in 语句，因为在 ts 中 for in 遍历的是数组的下标，而在 Swift 和 Kottlin 中遍历的是数组的元素，存在行为不一致。

- 添加元素到数组的末尾
```ts
const newLength = fruits.push('Orange')
// ["Apple", "Banana", "Orange"]
```
- 删除数组末尾的元素
```ts
const last = fruits.pop() // remove Orange (from the end)
// ["Apple", "Banana"]
```
- 删除数组头部元素
```ts
const first = fruits.shift() // remove Apple from the front
// ["Banana"]
```
- 添加元素到数组的头部
```ts
const newLength = fruits.unshift('Strawberry') // add to the front
// ["Strawberry", "Banana"]
```
- 找出某个元素在数组中的索引
```ts
fruits.push('Mango')
// ["Strawberry", "Banana", "Mango"]
const pos = fruits.indexOf('Banana')
// 1
```
- 通过索引删除某个元素
```ts
const removedItem = fruits.splice(pos, 1) // this is how to remove an item
// ["Strawberry", "Mango"]
```
- 从一个索引位置删除多个元素
```ts
const vegetables = ['Cabbage', 'Turnip', 'Radish', 'Carrot']
console.log(vegetables)
// ["Cabbage", "Turnip", "Radish", "Carrot"]
const pos = 1
const n = 2
const removedItems = vegetables.splice(pos, n)
// this is how to remove items, n defines the number of items to be removed,
// starting at the index position specified by pos and progressing toward the end of array.
console.log(vegetables)
// ["Cabbage", "Carrot"] (the original array is changed)
console.log(removedItems)
// ["Turnip", "Radish"]
```
- 复制一个数组
```ts
const shallowCopy = fruits.slice() // this is how to make a copy
// ["Strawberry", "Mango"]
```
### 访问数组元素

数组的索引是从 0 开始的，第一个元素的索引为 0，最后一个元素的索引等于该数组的 长度 减 1。

如果指定的索引是一个无效值，将会抛出 IndexOutOfBoundsException 异常

下面的写法是错误的，运行时会抛出 SyntaxError 异常，而原因则是使用了非法的属性名：

```ts
console.log(arr.0) // a syntax error
```