Creating an autonomous duplicate of a reversed array using JavaScript

Question

Creating an autonomous duplicate of a reversed array using JavaScript

Check out my code snippet here: http://jsfiddle.net/sepoto/Zgu9J/1/

I've started by creating a function that reverses an array:

function reverseArray(input) {
    var reversed = new Array;
    for(var i = input.length-1; i >= 0; i--) {
        reversed.push(input[i]);
    }

    //I attempted changing the return value to
    //return reversed.slice(0), but it did not create
    //an independent copy as intended
    return reversed;
}

The second array I created, pointOrigins2, is not truly independent of pointOrigins1. Any modifications made to pointOrigins2 are also reflected in pointOrigins1, which is not the desired behavior. Despite trying suggestions from StackOverflow such as using slice or a for loop, I have not been able to achieve the desired result yet, hence I created this fiddle.

Is there a way to produce an independent copy of the reversed array?

javascript arrays reverse

Answer 1

Answer №1

When creating a new independent array, ensure that you are also making independent copies of the items filling your arrays. To achieve this, consider the following approach:

function reverseArr(input) {
    var ret = new Array;
    for(var i = input.length-1; i >= 0; i--) {
        ret.push({
            positionx: input[i].positionx, 
            positiony: input[i].positiony, 
            index: input[i].index
        });
    }

    return ret;
}

This way, you will create new objects with identical properties in addition to the new array.

Answer 2

When creating a new independent array, ensure that you are also making independent copies of the items filling your arrays. To achieve this, consider the following approach:

function reverseArr(input) {
    var ret = new Array;
    for(var i = input.length-1; i >= 0; i--) {
        ret.push({
            positionx: input[i].positionx, 
            positiony: input[i].positiony, 
            index: input[i].index
        });
    }

    return ret;
}

This way, you will create new objects with identical properties in addition to the new array.

Answer 3

Answer №2

implement this algorithm

function reverseArrayElements(inputArr) {
var reversedArray = [];
for(var index = inputArr.length-1; index >= 0; index--) {
    reversedArray.push(inputArr[index]);
}
return reversedArray;
}

Answer 4

implement this algorithm

function reverseArrayElements(inputArr) {
var reversedArray = [];
for(var index = inputArr.length-1; index >= 0; index--) {
    reversedArray.push(inputArr[index]);
}
return reversedArray;
}

Answer 5

Answer №3

To easily reverse your array, make sure to clone it first!

The quickest method is:

var newArray = oldArray.slice();

Using concat works too. Here's an example:

Fastest way to duplicate an Array in Javascript - slice vs for loop

If slice doesn't create a copy for you, consider using numpy arrays and creating a deep copy like this:

np.copy(array);

For more information: http://documentationlink.com

Answer 6

To easily reverse your array, make sure to clone it first!

The quickest method is:

var newArray = oldArray.slice();

Using concat works too. Here's an example:

Fastest way to duplicate an Array in Javascript - slice vs for loop

If slice doesn't create a copy for you, consider using numpy arrays and creating a deep copy like this:

np.copy(array);

For more information: http://documentationlink.com

Answer 7

Answer №4

const flipArray = (arr) => {
    return [...arr].reverse();
}

Answer 8

const flipArray = (arr) => {
    return [...arr].reverse();
}

Answer 9

Answer №5

Your code is functioning correctly, though it could be shortened to

return input.slice().reverse();

//The following demonstrates that pointOrigins2 is not an independent copy of pointOrigins1
//Modifying pointOrigins2 also affects pointOrigins1
pointOrigins2[0].index++;

It's important to note that by modifying the pointOrigins2 array in this way, you are actually only altering the specific point object within both arrays. However, pointOrigins1 !== pointOrigins2.

If you want to modify one array independently from the other, you can do so like this

pointOrigins2[0] = {
    positionx: pointOrigins2[0].positionx, 
    positiony: pointOrigins2[0].positiony, 
    index:     pointOrigins2[0].index + 1
};

This ensures that pointOrigins1 remains unchanged. To have points with properties that can be modified without affecting other arrays, new points must be created.

Answer 10

Your code is functioning correctly, though it could be shortened to

return input.slice().reverse();

//The following demonstrates that pointOrigins2 is not an independent copy of pointOrigins1
//Modifying pointOrigins2 also affects pointOrigins1
pointOrigins2[0].index++;

It's important to note that by modifying the pointOrigins2 array in this way, you are actually only altering the specific point object within both arrays. However, pointOrigins1 !== pointOrigins2.

If you want to modify one array independently from the other, you can do so like this

pointOrigins2[0] = {
    positionx: pointOrigins2[0].positionx, 
    positiony: pointOrigins2[0].positiony, 
    index:     pointOrigins2[0].index + 1
};

This ensures that pointOrigins1 remains unchanged. To have points with properties that can be modified without affecting other arrays, new points must be created.

Creating an autonomous duplicate of a reversed array using JavaScript

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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