# JavaScript Array.from()

Array.from() lets you create array object from any object with a length property or any iterable object. It is a static method and hence it is not on `prototype`.

### Syntax
```
Array.from(object, mapFunction, thisValue)
```

`object` is an array-like object or iterable. Array-like objects can be String, Map, Set, etc.

`mapFunction` is the function which will be called on every item of the array. It is an optional parameter.

`thisValue` is the value to be used as `this` when executing `mapFunction`. It is also an optional parameter.

Let's see few applications of Array.from():

#### 1.  Converting string to array

```
Array.from("Hello!");          // ['H','e','l','l','o','!']
```

#### 2. Creating array of numbers with specified length

```
const numArray = Array.from({ length: 50 },(_, index)=>{
  return index;
});   
console.log(numArray);     // [0, 2, 3,....49]
```
 Here, first we created an object with length property and passed a value 50. Next, a function is passed which simply returns the index which ultimately serves as the element of our array. Had we not passed this function, the resulting array would be an array of length 50, but with all the elements as `undefined`.

#### 3. Creating a deep copy of an array

```
const num = [1, 2, 3];
const numCopy = Array.from(num);
num === numCopy;       // => false

```