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Cloned my array, and yet the original array keeps getting modified. Why?


By : Diana C. Prusza
Date : July 30 2020, 11:00 PM
I hope this helps you . This is because .slice() only performs a shallow copy, therefore some of the values are still referenced from the original array. Please see more detailed explanation in the answers to this question: What is the difference between a shallow copy and a deep copy with JavaScript arrays?
code :


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Cloned array gets the same value as original


By : user2968133
Date : March 29 2020, 07:55 AM
should help you out I have an array, and want to copy it so I can check if it has changed. , It's because the outer array is cloned, but not the 4 inner arrays.
code :
@table = [[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]]
@old_table = @table.clone
@old_table.object_id
# => 70198498995020 
@table.object_id
# => 70198498975440 (So far so good)

@old_table[0].object_id
# => 70198498975520 
@table[0].object_id
# => 70198498975520 (Same row id!)
@old_table = Marshal.load Marshal.dump(@table)

Changing a cloned array via Array.prototype.slice() affects the original


By : Dedy Arya Pradita
Date : March 29 2020, 07:55 AM
it should still fix some issue Slice returns a shallow copy of an array, so if you have an array of arrays, the array references will be copied as-is. One shortcut to doing a deep copy of an array, depending on the types of your data members, is to do the following instead of b=a.slice():
code :
var b = JSON.parse(JSON.stringify(a));
function arrayClone( arr ) {

    var i, copy;

    if( Array.isArray( arr ) ) {
        copy = arr.slice( 0 );
        for( i = 0; i < copy.length; i++ ) {
            copy[ i ] = arrayClone( copy[ i ] );
        }
        return copy;
    } else if( typeof arr === 'object' ) {
        throw 'Cannot clone array containing an object!';
    } else {
        return arr;
    }

}

Why does my original array get spliced if I splice the cloned array in JavaScript?


By : David
Date : March 29 2020, 07:55 AM
Any of those help Because of the assignment of c, you get the reference of the array coords.
Any change of coords does effect c, until a new value is assigned to c.
code :
var coords = [
         {lat: 39.57904, lng: -8.98094, type: "a"}, // A
         {lat: 39.55436, lng: -8.95493, type: "b"}, // B
         {lat: 39.56634, lng: -8.95836, type: "c"} // C
     ],
     c = coords.slice();

console.log(c);
coords[1].type = 'foo';
console.log(c);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Laravel: Looping through an array and converting it to a modified array with original array inside a key


By : Inwon Kang
Date : March 29 2020, 07:55 AM
I hope this helps you . I have a data array that contains food items and looks like this. , You could use Collections and do something like:
code :
$data = collect(json_decode($data, true))
    ->map(function ($item) {
        return collect($item);
    })
    ->groupBy(function ($item) {
        return trim(str_replace(['SMALL', 'MEDIUM', 'LARGE'], '', $item['name']));
    })
    ->map(function ($items) {

        if ($items->count() > 2) {

            return $items;
        }

        $parent = $items->first()->except('price');
        $parent->put('itemModifiers', $items);

        return $parent;
    });
->map(function ($items) {
    return $items->count() < 2 ? $items : $items->first()->except('price')->put('itemModifiers', $items);
});

Search filter nested array getting modified original array after Object.Assign


By : zxpan
Date : March 29 2020, 07:55 AM
Hope this helps Trying to implement Search Filter on 2 level nested array based on the digits: if the digits/number match any sequence in my datastructure the results need to be exactly matched with searchcriteria: , your problem is in this lines:
code :
filterTreeRange.treeRanges = filterTreeRange.treeRanges.filter(...);
filTreeRange.treeregistered = filTreeRange.treeregistered.filter(...);
const data = [{
  tree: "17200",
  treeRanges: [
    {
      id: 134055,
      strttreeNum: "5308550000000000000",
      endngtreeNum: "5308559999999999999",
      treeregistered: [
        {
          id: 9,
          branch: "12345678989895559"
        },
        {
          id: 10,
          branch: "78912349494945449"
        }
      ]
    },
    {
      id: "23175",
      strttreeNum: "1234309999999999999",
      endngtreeNum: "3466309999999999999",
      treeregistered: [
        {
          id: 14,
          branch: "5500001231234234"
        },
        {
          id: 15,
          branch: "5598761234444234"
        }
      ]
    }
  ]
}];

const treeRegisteredIncludes = searchTerm => treereg => treereg.branch.includes(searchTerm)
const treeRangesIncludes = searchTerm => treeinRange =>
    treeinRange.strttreeNum.includes(searchTerm) ||
    treeinRange.endngtreeNum.includes(searchTerm) ||
    treeinRange.treeregistered.some(treeRegisteredIncludes(searchTerm))
const itemIncludes = searchTerm => item => 
    item.tree.includes(searchTerm) ||
    item.treeRanges.some(treeRangesIncludes)

const filterByTerm = (treeRange, searchTerm) => !searchTerm ? treeRange :
    treeRange.filter(itemIncludes(searchTerm))
    .map(filterTreeRange =>
      Object.assign({}, filterTreeRange, {
        treeRanges: filterTreeRange.treeRanges
          .filter(treeRangesIncludes(searchTerm))
          .map(filTreeRange =>
            Object.assign({}, filTreeRange, {
              treeregistered: filTreeRange.treeregistered.filter(treeRegisteredIncludes(searchTerm))
            })
          )
      })
    );


console.log({
  filteredBySearchTerm: filterByTerm(data, "444"),
  original: data
});
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