Removing element of array via underscore.js

Question

I am using underscore.js on my front-end and I want to remove a pair of values from a two-dimensional array. What am I doing wrong, because the below doesn't work?

How I add the element to array:

google.maps.event.addListener(map, 'click', function (event) {
  var latitude = event.latLng.lat()
  var longitude = event.latLng.lng()
  coordinatesForMarker.push([latitude, longitude])

How I am trying to remove:

google.maps.event.addListener(marker, 'click', function (event) {                                                
  var latitude = event.latLng.lat()
  var longitude = event.latLng.lng()
  var newArray = _.without(coordinatesForMarker, ([latitude, longitude]))

Is there another solution, one not requiring a library?

Are you actually assigning newArray to coordinatesForMarker? — Originato
– Originato, Commented May 13, 2017 at 8:47

taile · Accepted Answer · 2017-05-13 08:48:42Z

1

Let's try with findWhere

var arr = [[
  1,2
], [
  3,
  3
], [
  5,
  6
]];

//substract third
arr = _.without(arr, _.findWhere(arr, [5, 6]));
console.log(arr);

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>

answered May 13, 2017 at 8:48

taile

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Comments

clinton3141 · Accepted Answer · 2017-05-13 09:01:51Z

1

Is there another solution, one not requiring a library?

Absolutely! You can achieve this without a library by using native array method filter. It takes a function as an argument which returns true if you'd like to keep the element, and false if you'd like to exclude it.

var coordinatesForMarker = [[41.482583, -82.687353], [52.986944, -1.882778], [35.706336, 139.753277]];

var latitude = 52.986944;
var longitude = -1.882778;

var newArray = coordinatesForMarker.filter(function (coord) {
  return coord[0] !== latitude && coord[1] !== longitude;
});

console.log(newArray)

edited May 13, 2017 at 9:01

answered May 13, 2017 at 8:56

clinton3141

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Comments

marpme · Accepted Answer · 2017-05-13 08:56:32Z

Since your array contains references of arrays the comparison isn't that easy, but let me explain that in a more detailed way.

For example you have that Array:

myArray = [ [ 21, 222 ], [ 214, 314 ] ]

The array actually just contain the references to their array so the "internal" array looks something like this:

myArray = [ arrc@0x212414 , arrc@0x253211 ]

and if you now try to compare an array which you parsed into the without function of underscore, the library just compares those references if they are equally.

So a better better way to solve your problem might be to filter the array and define an own function on how to correctly compare those arrays!

newArray = myArray.filter((element) => { element[0] !== event.lang && element[1] !== event.long })

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