JS Remove Entries from 2D array

Question

Totally newbie to JS so apologise for the probably obvious solution to this issue!

I'm trying to write a bit of code for use in google sheets that basically removes elements of a 2D array if the 3rd value in each nested array is empty eg.

[[1,2,3],[4,5,,],[7,8,9],[,,,]

would become

[[1,2,3],[7,8,9]]

I've currently got:

if (bkLoc=='HALL'){
      var sumRng = sh.getRange('MIC_SUMM').getValues();
      for (var i =0; i<sumRng.length ; i++){
        if(sumRng[i][2] !== (undefined || '' || null)){
          micSumm.push(sumRng[i]);
        }
      }
    }

But the output seems to contains loads of empty arrays almost like its pushing every loop and I'm not sure why.

Any help would be gratefully received!

EDIT1: So with the help of you guys I got it to work. Using Nikhils answer I am now using this for the IF

if (bkLoc=='HALL'){
      var sumRng = sh.getRange('MIC_SUMM').getValues();
      for (j =0; j<sumRng.length ; j++){
        var x = sumRng[j][2];
        if(x != 0 && x != '??'  && x != undefined){
          micSumm.push(sumRng[j]);
        }
      }
    }

But to be honest I don't really understand it. My understanding was || is OR so in my original code

if(sumRng[i][2] !== (undefined || '' || null))

If the tested content DOESN'T CONTAIN undefined OR "" OR null , the if statement should be true. I thought && meant AND so I'm unclear as to why that ever passes

Apologies for being so dumb!

Cheers

Answer 1

In your current if condition, undefined || '' || null undefined || '' || null undefined || '' || null evaluates to null . Hence, the condition eventually becomes sumRng[i][2] !== null .

However, as you need to check for undefined and '' too, you will need to update your condition

From

if(sumRng[i][2] !== (undefined || '' || null)){

to

if(sumRng[i][2] !== undefined && sumRng[i][2] !== '' && sumRng[i][2] !== null){

Answer 2

Assuming you've defined micSumm somewhere and started out with a blank array in it ( var micSumm = []; ), then you're on the right track, the issue is here:

if(sumRng[i][2] !== (undefined || '' || null)){

That's not how you do a check against multiple values in JavaScript. The way that's evaluated is:

1. sumRng[i][2] is evaluated; let's call the resulting value left
2. undefined || '' undefined || '' is evaluated, the result is '' ; let's call it temp ¹
3. temp || null temp || null ( '' || null ) is evaluated, the result is null ; let's call that right
4. The result of left !== right is evaluated

So you end up only checking for null , not undefined or '' .

Instead:

var value = sumRng[i][2];
if (value !== undefined && value !== '' && value !== null) {

Or you can take advantage of the fact != undefined also checks for null :

var value = sumRng[i][2];
if (value != undefined && value !== '') {

...but that can be a bit less clear.

---

¹ Why does undefined || '' undefined || '' result in '' ? Because an expression a || b a || b is evaluated like this:

1. Evaluate a
2. If the value from Step 1 is truthy , make that the result of the || operation
3. Otherwise, evaluate b and make that the result of the || operation

undefined is falsy , not truthy . (A falsy value is any value that coerces to false when used as a boolean. The falsy values are undefined , null , "" , 0 , NaN , and of course, false . All other values are truthy .)

Answer 3

You could also use filter(which is supported by apps-script):

var filteredArr =  sumRng.filter(function(e) {return e[2];})

Note that you're getting a 2D array with a specific rectangular dimension. So, there's no possibility of a value being undefined . Unless you specifically made a value null , null isn't returned. As noted in the comments below, the above also filters out 0 and boolean false. So, You can use

sumRng.filter(function(e) {return e[2].toString();})

or

sumRng.filter(function(e) {return e[2] || e[2] === false || e[2] === 0;})

References:

Array#filter
Primitives
null
Comparison Operators
Truthy

Answer 4

I still struggle with the why the original OR method I had doesn't work. In fact I went over to reddit to try and see if I could get anymore clarification but still it won't go in. But I appreciate all your help trying.

I did get an alternative solution to my conundrum though which seems a more condensed version of what I was using. That was simply this (courtesy of user insertAlias)

if(sumRng[i][2]){}

Apparently that will only pass for anything truthy so seems to fit the bill. But please point out any shortcomings