How to create an array from an array?

How to create an array from an array?

Examples Array from a String Array from a Set Array from a Map Array from an Array-like object (arguments) Using arrow functions and Array.from() Sequence generator (range)

How to create an array of unique values in JavaScript?

Imagine you have a JavaScript array that contains many elements, some of which are duplicated: Your goal is to remove the duplicates and leave only one entry per value: You might write a for-loop, or use a map or filter to get this result.

How does Array.from ( ) work in JavaScript?

The Array.from() method creates a new, shallow-copied Array instance from an array-like or iterable object.

How do you add values to an array?

In an array, it would have been added and the length would be 4. There are two ways to add values to a Set. Firstly by using the add method as above. Secondly by passing an array to the constructor ( new Set () ): Duplicated values are also removed if they are included in the initial array:

How to add custom functions to array object?

Consider someone using two Javascript frameworks that both try to extend the Array in a similar way and pick the same method name. Or, consider someone forking your code and then putting both the original and forked versions on the same page. Will the custom enhancements to the Array object still work?

Is the array object prototype a bad idea?

In the case of the Array object prototype, it is an especially bad idea, because it has the potential to interfere with any piece of code that iterates over the members of any array, for instance with for .. in. To illustrate using an example (borrowed from here ):

How to convert an array to an iterator?

If you’d like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request. An array-like or iterable object to convert to an array.