JS ES6: Array.from()

1.  method 

2. creates a new, shallow-copied Array instance from an array-like or iterable object.

3. The length property of the from() method is 1.

4. In ES2015, the class syntax allows sub-classing of both built-in and user-defined classes.
   : As a result, static methods such as Array.from() are "inherited" by subclasses of Array, and create new instances of the subclass, not Array.

 

[Syntax]

Array.from(arrayLike [, mapFn [, thisArg]])
// has the same result as Array.from(obj).map(mapFn, thisArg)
// except that it does not create an intermediate array.

arrayLike		An array-like or iterable object to convert to an array.
		- array-like objects: objects with a length property and indexed elements.
		- iterable objects: objects such as Map and Set.
mapFn	optional	Map function to call on every element of the array. Which allows you to execute a map() function on each element of the array being created.
thisArg	optional	Value to use as this when executing mapFn.

 

[Return Value]

A new Array instance.

 

[Examples]

1. Array from a String

2. Array from a Set

3. Array from a Map

4. Array from an Array-like object (arguments)

5. Using arrow functions and Array.from()

6. Sequence generator (range)

 

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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from