Filtering nested array in js

Question

Let's say I have this nested arrays structure:

    [
    ["qltdm", Array(1)]
    ["qltdm", Array(0)]
    ["qlctf", Array(0)]
    ["qlctf", Array(1)]
    ]

I need to filter them in a way that first values cannot be duplicates, and that precedence have the second value (array) which is greater then 0.

So, in short to be left with this:

    [ 
    ["qltdm", Array(1)]
    ["qlctf", Array(1)] 
    ]

Help is appreciated.

Have you tried anything so far?

Baboo
– Baboo

2018-10-21 11:03:05 +00:00
Commented Oct 21, 2018 at 11:03 — Baboo
– Baboo, Commented Oct 21, 2018 at 11:03

Artyom Amiryan · Accepted Answer · 2018-10-21 11:12:18Z

3

const arr =  [
  ["qltdm", Array(1)],
  ["qltdm", Array(0)],
  ["qlctf", Array(0)],
  ["qlctf", Array(1)]
];


const newArr = [...new Set(arr.filter(o => o[1].length))]

Here it will filter only values where nested array length is bigger 0, and will add it in Set, Set only can contain unique values, so duplicate values will not be added here, after that Set values will be spreaded in new array by ... operator

edited Oct 21, 2018 at 11:12

answered Oct 21, 2018 at 11:10

Artyom Amiryan

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4 Comments

Artyom Amiryan Over a year ago

@NirTzezana there is babeljs.io, which can be used for those browsers, why using old ES5, if there is ES6+?

Nir Tzezana Over a year ago

Of course babel is an option, I just noted a fact (if OP is going to test this on IE11 and downwards).

Perp Over a year ago

Very nice, I considered using Set in some capacity, but this solution eluded me. Performance wise this is ok, right ? Using set only to get unique values and then spread it in new array ?

Artyom Amiryan Over a year ago

yes with performance it should be ok, Set is used for getting unique values, also Set is working faster than arrays, because Set doesn't use loops, you can also do not spread Set in new array if you want to use it as Set and increase your performance

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