How to remove each object of certain type from array

Question

Within my Angular controller I have created a method which is attached to a click handler on my scope. This click handler checks to see whether a checkbox is checked or unchecked and either pulls the associated objects out of an array or puts them back in.

My else block, where I push objects back into the array, works great. However, my if block where I attempt to splice these objects from the array does not work.

Here's the relevant code:

vm.checkToggle = function(isChecked, value) {
  if (!isChecked) {
    var length = vm.markers.length;
    for (var i = 0; i < length; i++) {
      if (vm.markers[i].type === value) {
        vm.markers.splice(i, 1);
      }
    }
  } else {
  ...
};

I believe what is happening is that my array's length shrinks each time I splice from it, so I inevitably run into a Cannot read property 'type' of undefined error halfway through the loop. How could I go about handling removing these objects from the array without running into this issue?

Iterate backwards over the array so your indexes don't change. — Georgette Pincin
– Georgette Pincin, Commented Aug 9, 2015 at 17:02
@GeorgettePincin, thank you! for (var i = length - 1; i >= 0; i--) worked like a charm! If you want to toss that up as an answer I'd love to give you credit for your help. — MattDionis
– MattDionis, Commented Aug 9, 2015 at 17:06
A simple solution to this would be to use Array.prototype.filter. — ryeballar
– ryeballar, Commented Aug 9, 2015 at 17:10
No problem at all. I actually was asked this for a coding challenge during an interview once...so good for you to run into it! — Georgette Pincin
– Georgette Pincin, Commented Aug 9, 2015 at 17:11

MattDionis · Accepted Answer · 2015-08-09 17:46:27Z

1

You have to iterate backwards over the array so your indexes don't shift. Something like this (not tested)

vm.checkToggle = function(isChecked, value) {
  if (!isChecked) {
    var length = vm.markers.length;
    for (var i = length - 1; i >= 0; i--) {
      if (vm.markers[i].type === value) {
        vm.markers.splice(i, 1);
      }
    }
  } else {
  ...
};

edited Aug 9, 2015 at 17:46

MattDionis

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answered Aug 9, 2015 at 17:08

Georgette Pincin

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