Combining nested arrays into a single array with unique items

Question

Suppose I have an object like this:

 hex_ids = [
    ["8d267451c3858ff", "8d267451c385bbf", "8d267451c385b3f", "8d267451c385b7f", "8d267451c3ae6bf", "8d267451c3ae6ff", "8d267451c3ae67f", "8d267451c3aa93f"], 
    ["8d267451c3aa93f", "8d267451c3ae2ff", "8d267451c3ae27f", "8d267451c3a8cbf", "8d267451c3a8dbf", "8d267451c3a8d3f", "8d267451c3ac6ff"]
 ]

The array has 2 nested array, each with a different length. At least one item in each nested array also exists in the other. What I want to do is combine these 2 nested arrays into a single array with unique items and eliminate any redundancies like this:

hex_ids = ["8d267451c3858ff", "8d267451c385bbf", "8d267451c385b3f", "8d267451c385b7f",
"8d267451c3ae6bf", "8d267451c3ae6ff", "8d267451c3ae67f", "8d267451c3aa93f", "8d267451c3ae2ff", 
"8d267451c3ae27f", "8d267451c3a8cbf", "8d267451c3a8dbf", "8d267451c3a8d3f", "8d267451c3ac6ff"]

What is the easiest method to do this?

const newArray = Array.from(new Set(hex_ids.flatMap(item => item))) — secan
– secan, Commented Aug 3, 2021 at 14:09
@secan - No reason to use flatMap, we have flat, avoiding the callback. — T.J. Crowder
– T.J. Crowder, Commented Aug 3, 2021 at 14:13
... actualy using flatMap() is pointless when a simple flat() would do, as you can see in the answer from @Spectric — secan
– secan, Commented Aug 3, 2021 at 14:13
@T.J.Crowder, yep, I realized it when I saw the answer from Spectric but thanks anyway :) — secan
– secan, Commented Aug 3, 2021 at 14:15

Spectric · Accepted Answer · 2021-08-03 14:07:15Z

5

Flatten the array with Array#flat and get the unique values:

const array = [
    ["8d267451c3858ff", "8d267451c385bbf", "8d267451c385b3f", "8d267451c385b7f", "8d267451c3ae6bf", "8d267451c3ae6ff", "8d267451c3ae67f", "8d267451c3aa93f"], 
    ["8d267451c3aa93f", "8d267451c3ae2ff", "8d267451c3ae27f", "8d267451c3a8cbf", "8d267451c3a8dbf", "8d267451c3a8d3f", "8d267451c3ac6ff"]
 ]
const result = [...new Set(array.flat())];
console.log(result);

answered Aug 3, 2021 at 14:07

Spectric

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1 Comment

gwydion93 Over a year ago

Wow, that worked great! Literally the simplest and cleanest solution and I can't believe I've never seen .flat before.

Mohit Agrawal · Accepted Answer · 2021-08-03 15:49:26Z

-1

var arr=[];

for(let i of hex_ids){
 arr=arr.concat(i)
}
console.log(Array.from(new Set(arr)))

answered Aug 3, 2021 at 15:49

Mohit Agrawal

1

1 Comment

Taco Over a year ago

Welcome to StackOverflow! Please take some time to elaborate on your answer and tell the OP and future readers, why, your particular solution works.

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