The `slice` method in an `array` returns a shallow copy of a portion of the array based on the `start` and `end` index passed.

## 3 Uses for Array Slice in JavaScript

1. Copy an array.
2. Get the first N array.
3. Remove an element at a specific index.

Here’s a brief refresher on the slice method:

• Both `start` and `end` is an optional argument.
• By default the `start` is `0` and `end` is `array.length`
• `end` of an index is not considered. This means if you `slice` an array passing `start` as `0` and `end` as `5`, then elements from `0th` to `4th` index will be copied.
• The `slice` doesn’t affect the `source` array from which we are performing `slice`.
• It only creates a `shallow copy`.
• We can also give a negative value for the `start` and `end` index, which indicates an offset from the end of the array. So, we can have a -1 point to last element.
``````var numbers = [0, 1, 2, 3, 4, 5];
var newNumbers = numbers.slice(1,4);
newNumbers;   //[1,2,3]``````

## How to Use Array Slice in JavaScript

Below are some common ways you can use the array slice method in JavaScript.

### 1. Use Array Slice to Copy an Array

``````var numbers = [0, 1, 2, 3, 4, 5];
var copiedNumbers = numbers.slice(0, numbers.length);
copiedNumbers; // [0, 1, 2, 3, 4, 5]``````

By default, the start index is 0 and the end index is the length of the array. By applying that, we see:

``````var numbers = [0, 1, 2, 3, 4, 5];
var copiedNumbers = numbers.slice();
copiedNumbers; // [0, 1, 2, 3, 4, 5]``````

More on JavaScript: What Are JavaScript Algorithms and Data Structures?

### 2. Use Array Slice to Get the First N Array

This is similar to copying an array. Instead of passing the `end` index value as `arrayLength`, pass `end` index as n.

``````function firstNItems(n, numbers =[] ) {
if(n >= 0) {
return numbers.slice(0, n);
}
return [];
}
firstNItems(0, [1,2,3]); // []
firstNItems(2, [1,2,3]); // [1,2]``````

More on JavaScript: 5 Ways to check If an Object Is Empty in JavaScript

### 3. Use Array Slice to Remove an Element at a Specific Index

Using the `shift` and `pop` method, you can remove an element at the front and end of the array respectively. But there is no method to remove an element at a specific index. For that, you can use the slice method.

This will allow you to do the following:

• Create an array that contains all elements of the array before the index.
• Create an array that contains all elements of the array after the index.
• Join two arrays.
``````function removeElementAt(arr, index) {
let frontPart = arr.slice(0, index);
let lastPart  = arr.slice( index+1 ); // index to end of array
return [...frontPart, ...lastPart];
}
let numbers = [1,2,3,4,5];
removeElementAt(numbers, 2); [1,2,4,5];``````
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