Javascript Copy Matrix

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Michael Zippo 04.11.2021

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In JavaScript , copying an array is not as easy as using the assignment operator (=) to create a duplicate . If you’ve tried this before, you’ll be surprised to find that it only links to the original list. What is the problem ?

In this guide, we will explain how to copy a JavaScript array. We’ll take a look at the code for three JavaScript array copying strategies so you can get started copying arrays.

The problem with copying JavaScript arrays

At one level, the " = & Rdquo; The operator creates a copy of an array in a new variable . However, this is more of a pointer than a copy. This is because the "=" operator creates a reference to an original array. It does not create a duplicate of the existing table.

Let’s try to create a copy of an array using the assignment operator without any other code:

Our code returns:

It seems that our table has been copied. "Fruit" contains all the values ‚Äã‚Äãfrom our "berries" array .

Now let’s try to add an element to the "fruits" array folder:

We have added "Melon" to the fruit series. Next, we print the values ‚Äã‚Äãfor " fruits " and " berries " to the console:

Both "fruits" and "berries" contain the same values. This is because technically we haven’t cloned our bay. We just created a reference to this one.

Each time we manipulate the "berries" array , the changes will be made in the field of the "fruits" array .

How to copy a JavaScript array

The assignment operator does not copy an array. We have to use another approach. Lucky for us, there are plenty of ways to make a copy of a painting. The three main approaches are:

• Using the spread operator
• Using a for loop
• Using Array.from

Let’s discuss it one by one.

Using the spread operator

The spread operator is a feature introduced in JavaScript ES6. It provides access to content from . an iterable This operator is often used to make a shallow copy of an array

The operator spread has three points as an ellipse (& hellip;).. Let’s create a copy of our "berries" array from before:

We used the spread operator to create a copy of our array. We check the values ‚Äã‚Äãin our arrays to make sure they are correct:

Our code returns:

The value & ldquo; Melon " Has been added only to" fruits " Carrier. In fact, we used the broadcast operator to create a duplicate vector " berries " . Now the table " fruit " is its own table. His values are separated by the tables "berry" .

using a loop

the proven, the use of a for loop is a good way to create a copy of a painting .

This method may not be preferred as a propagation operator because it requires multiple lines of code. However , a for loop does copy an object.

We have declared two lists: berries and fruits. Fruits is initially an empty list. We have so used a for loop to iterate through all the elements of the l iste "berries" . For each item in the list, the value is copied to the "fruit" array folder .

Let’s run our test to see if our arrays are separated:

Our code returns:

Success ! "Berries" and "fruit" are two separate tables.