How to skip the undefined values in an array while running the for loop

Question

I have several checkboxes in my webpage table. When the user checks a checkbox (eg number 10) , a marker for number 10 and is saved to my array "currentMarkers" in the 10th position.

this.currentMarkers[j] = mymarker;  // where j is the number selected by user

Now only the 10th position in the array " currentMarkers" has a value and the rest are undefined since only one checkbox is clicked.

Now the problem I'm facing is that, when i click a main check box i need to clear all the markers in the map by removing the markers from the array. But since currentMarkers[0] has an undefined value ,it shows an error and stops and cannot go forward and remove the currentMarkers[1] , currentMarkers[2] and so on .

for(let m =0; m <12; m++){
currentMarkers[m].remove(); // stops as currentMarkers[0] undefined.
}

NOTE: If i use the clear array methods the markers will be still in the map. I can only use the .remove() method to remove the markers one by one from the map, and that's why i used the for loop

Is there any way i can look which array values actually have data and use a for loop to iterate through them?

Any help is appreciated. Thanks a lot for your time.

Can you just check if currentMarkers[m] exists before trying to call the remove method? If optional chaining is available, this could be as easy as currentMarkers[m]?.remove(). If not, you could do something like currentMarkers[m] && currentMarkers[m].remove() — Nick
– Nick, Commented Jul 4, 2021 at 23:41

Slava Knyazev · Accepted Answer · 2021-07-04 23:40:53Z

1

The simplest method would be to check for it, and invoke continue to skip to the next iteration of the loop:

for(let m =0; m <12; m++){
   if (currentMarkers[m] == undefined) continue;
   currentMarkers[m].remove();
}

answered Jul 4, 2021 at 23:40

Slava Knyazev

6,0991 gold badge27 silver badges52 bronze badges

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

1 Comment

jot Over a year ago

Hey thanks for answering !! But for some reason it still shows that error. The one @thomson gave seems to work.

Thomson Mixab · Accepted Answer · 2021-07-04 23:44:07Z

0

To remove only array element that has value. https://love2dev.com/blog/javascript-remove-from-array/

for(let m =0; m <12; m++){
    if(currentMarkers[m] != undefined || currentMarkers[m] != null) 
    {
        currentMarkers[m].remove(); // stops as currentMarkers[0] undefined.
    }
}

answered Jul 4, 2021 at 23:44

Thomson Mixab

6425 silver badges8 bronze badges

Collectives™ on Stack Overflow

How to skip the undefined values in an array while running the for loop

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related