Splicing empty array on Javascript

Question

I am trying to remove the empty array elements (from a csv file) by using the splice() function.

The array elements are stored inside csv.data:

csv.data.forEach(function(item,index) {
    if (item.length < 2) { // don't want anything less than two
        csv.data.splice(index,1); 
        }
    });

This works, but it still returns me two empty arrays (lines) in the csv file, originally, there are six empty lines, but it skips the two empty lines.

Am I doing anything wrong?

This is the csv.data

[
 [
  "1212",
  "okay",
  ""
 ],
 [
  ""
 ],
 [
  ""
 ],
 [
  ""
 ],
 [
  ""
 ],
 [
  ""
 ],
 [
  ""
 ]
]

Expected

[
 [
  "1212",
  "okay",
  ""
 ],
]

Possible duplicate of Remove empty elements from an array in Javascript — Herohtar
– Herohtar, Commented Mar 22, 2018 at 13:16
@NinaScholz it absolutely correct. Any type of modifying of location of elements of an array, whether moving, adding, or removing, in a forEach could have undesired consequences. You would be better using a for loop and adding logic to keep track of where you were (but only as a fun way to understand the logic and why it breaks). But, that's also not the best solution here. I just thought I would reiterate why these modifications are not recommended in a forEach. — adprocas
– adprocas, Commented Mar 22, 2018 at 13:19
That update is not that helpful, it looks now like an array of array. Could you try doing console.log(JSON.stringify(csv.data, null, " ")) and copy post that. — Keith
– Keith, Commented Mar 22, 2018 at 13:24

Reinstate Monica Cellio · Accepted Answer · 2018-03-22 13:29:21Z

6

It's not a good idea to use splice inside the loop. You can miss some indexes. You can use filter function instead of forEach

var csv = { data: [["1212", "okay", ""], [""], [""], [""], [""], [""], [""]] };

csv.data = csv.data.filter(items => items.length > 1);

console.log(csv.data);

edited Mar 22, 2018 at 13:29

Reinstate Monica Cellio

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answered Mar 22, 2018 at 13:15

Suren Srapyan

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14 Comments

Suren Srapyan Over a year ago

It will return an array with same data, but filtered., which is in the csv.data.

Reinstate Monica Cellio Over a year ago

Please update the question and add an example of csv.data as this answer is 100% correct, for the question as it currently stands.

Reinstate Monica Cellio Over a year ago

I've added the array and a code snippet, to show this working exactly as described.

Suren Srapyan Over a year ago

@Archer Thanks.

Reinstate Monica Cellio Over a year ago

@zuif - you're 100% wrong. This code works and if you just click a simple button then you'd see it. If this answer is in any way incorrect then it's because you have failed to describe the problem.

|

Keith · Accepted Answer · 2018-03-22 13:31:57Z

1

If you also wanted to remove empty elements from the top array, you could do another filter.

eg.

const a = [ [ "1212", "okay", "" ], [ "" ], [ "" ], [ "" ], [ "" ], [ "" ], [ "" ] ];

const ret1 = a.map((b) => b.filter((f) => f));
console.log(ret1);

//if you also want to remove empty elements from top array.
const ret2 = ret1.filter((f) => f.length);
console.log(ret2);

answered Mar 22, 2018 at 13:31

Keith

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Comments

Nina Scholz · Accepted Answer · 2018-03-22 13:29:05Z

0

You could iterate the array from the end and splice without colliding with the index.

var array = [["1212", "okay", ""], [""], [""], [""], [""], [""], [""]],
    i = array.length;
    
while (i--) {
    if (array[i].length < 2) {
        array.splice(i, 1);
    }
}

console.log(array);

answered Mar 22, 2018 at 13:29

Nina Scholz

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1 Comment

Dhiraj Over a year ago

Thanks, Nina Scholz to the rescue !

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