How to duplicate an array with itself using lodash?

Question

I'm currently doing the following:

_.map(_.shuffle(myMapping), (item, index) => (
  <p>{item.title}</p>
))

How can I essentially duplicate myMapping so that myMapping = myMapping + myMapping?

I'm not trying to remove duplicate, I was the copy to be 2x in length.

bhantol · Accepted Answer · 2018-02-05 22:15:33Z

2

Using lodash

var myMapping  = [1,2,3,4,5]
var myMappingPlus = _.flatten(
   _.map(myMapping, function(v) { return [v, v];});
 );

You map an element to an array and then flatten it.

answered Feb 5, 2018 at 22:15

bhantol

9,6368 gold badges48 silver badges84 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

You can shuffle the whole thing _.shuffle(myMappingPlus) if you like.

Barmar · Accepted Answer · 2018-02-05 22:30:33Z

0

The .concat() method concatenates arrays:

_.map(_.shuffle(myMapping.concat(myMapping)), (item, index) => (
  <p>{item.title}</p>
))

answered Feb 5, 2018 at 22:30

Barmar

789k57 gold badges554 silver badges669 bronze badges