Tags down


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 :

Share : facebook icon twitter icon

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
# => 70198498995020 
# => 70198498975440 (So far so good)

# => 70198498975520 
# => 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();

coords[1].type = 'foo';
.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) ||
const itemIncludes = searchTerm => item => 
    item.tree.includes(searchTerm) ||

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

  filteredBySearchTerm: filterByTerm(data, "444"),
  original: data
Related Posts Related Posts :
  • Why doesn't the .remove() method also affect the variable it's being set on?
  • React hooks error: Rendered more hooks than during the previous render
  • How to create a completely new Keyword in JavaScript?
  • When summing values from 2 arrays how can I cap the value in the new array?
  • A pop up window to login in
  • How to push spacebar action to array
  • How do i highlight a specific table row depending on the url
  • Truly Weak Reference Event Emitter / Dispatcher: is it possible?
  • Conditionally render a a background image based on current view using React Router
  • Can not retrieve component template while routing
  • How to keep the checkbox status after refreshing the page
  • Array of Object - divide information as per values in it
  • Calculating body style height (for horizontal scroll) in javascript not working
  • How to exclude certain values from randomly generated array
  • Change colour of selected <li>
  • Formatting date object in an Array with moment is giving an unexpected result
  • combineLatest operator alternative
  • 'object' is never reassigned. Use 'const' instead
  • What does the spread operator in ES6 convert to in older JavaScript? Is it costlier than array.concat?
  • Get duplicates in array of strings and count number of duplicates
  • How to fix React Redux and React Hook useEffect has a missing dependency: 'dispatch'
  • Call a ajax request only if there are ajax requests added to the list
  • Using the jQuery each function to count divs with the same class
  • FInding out the Harshad number
  • angular route is not working and not changing current view
  • Callback executed before function finishes execution
  • How to create subfolder and document on Firestore web?
  • Scroll algorithm -- improving fetch and display of data
  • New To Programming World
  • Using mongorestore to insert many documents into a temp collection
  • How to extend localStorage across devices (without DB)
  • How to do pre increment without using ++I?
  • Retrieve filterViewId from batchUpdate request addFilterView
  • What is the corresponding instanceof target for text nodes?
  • How to Test the API by Token on Postman?
  • How to set Bootstrap dropdown menu on hover?
  • In Slate.js editor.apply(operation) is not applying "split_node" operations correctly
  • No data in GET response
  • Javascript using if else to determine array value
  • Error when I run npm install Error: 404 Not Found: 7zip-bin@~4.1.0
  • I want to modified my JSON output using JS
  • Error in Entry module not found and in webpack
  • Submit button is not submitting the form after changing the button type
  • Why is the function created is not working.?
  • How can I do day timer with javascript?
  • Tap screen to trigger autofocus with getUserMedia
  • Unable to bind html table data to mvc controller Model
  • How can I simply work around a missing JS property in an object in an object?
  • How to add anything at a specific position in a string using vanilla javascript
  • using async methods inside of array.map() in javascript
  • Math.random() vs random() in Khan Academy Computer Programming
  • Call two functions with onPress in react native
  • Use a global variable inside promise javascript
  • Turn array of objects into array of properties
  • Would having a Pure Class concept make sense or not?
  • Why catch invoked with success promise?
  • Match whole word if it meets a condition
  • Inserting items into array with bracket syntax doesnt affect length?
  • adding value inside an input - React
  • How does setInterval() run independently of sequential execution?
  • shadow
    Privacy Policy - Terms - Contact Us © voile276.org