
 In TypeScript, **arrays** are a collection of homogeneous elements stored in contiguous memory locations. Elements in arrays can be accessed by index, and indices begin from `0`.


The following diagram represents an array where the number *1* is stored at index `0`. The number *2* is stored at index `1`, and so on.

# 
## Initialization
In TypeScript, arrays can be initialized in two ways:
## 1.  Using square brackets

### Syntax
```
let arrayName:dataType[] = [element1, elment2,...]
```
### Example

In the following code, we are creating the array `weeks:string[]`, where `weeks` is the array's name, and `string` is the element's *data type*  in the array.

The right side of the `=` operator depicts the assignment of the values in an array separated by a comma `,`: `["monday","tuesday"]` to the array.




let weeks:string[] = ["monday","tuesday"]
console.log(weeks)

## 2. Using generic array type
### Syntax
```
let arrayName:Array<datatype> = [element1, element2, ...]
```

### Example

In the following code, `weeksAndNumbers:Array<string>` is used to create an array.  `weeksAndNumbers` is the array's name and the array type in a generic way. The `Array<string>` is specified by the data type of the first element in the array.




let weeksAndNumbers:Array<string> = ["monday","tuesday"]
console.log(weeksAndNumbers)

Running the code snippet below will throw the error `Type 'number' is not assignable to type 'string'` because we are adding a number to a string array.

To overcome the issue, we can specify the data as `any`.

//passing number to string array
let weeks:string[] = ["monday",5]
console.log(weeks)

//passing number to string array
let weeks:any[] = ["monday",5]
console.log(weeks)

#  
## Multi-type arrays
We have seen how to create arrays, but we have some restrictions on passing elements of different data types to an array. 

Even though the `any` type is available, it is not ideal to use for every scenario. Therefore, we will discuss passing multiple data types by separating them with `|`.

In the following code, we pass elements of `string` and `number` to an array by the `|` separator. We can add as many elements as we want.

//we are informing to typescript that the array,
//may contain a string or number or both.
let weeks:(string | number)[] = ["monday",5]
console.log(weeks)

# 
## Accessing array elements

To access any array element, use the index for that element enclosed in square brackets, `[]`.


let primes:number[] = [2,3,5,7]

//accessing first element at index 0
console.log(primes[0])

//accessing last element at index 3
console.log(primes[3])

# 
## Multi dimensional arrays

We can create multi-dimensional arrays just by specifying another square bracket `[]` for each dimension.

In the following code, we create a `2D` array.

//2D Array
let num:number[][] = [[1,2,3],[4,5,6],[7,8,9]]
console.log(num)

//accessing first element
console.log(num[0][0])

What are TypeScript arrays?

In TypeScript, arrays hold homogeneous elements accessed by index. They can be initialized using square brackets or the generic array type.