When dealing with arrays in JavaScript, Slice vs Splice is a popular subject that tends to puzzle developers. Though both functions are employed to handle arrays, they operate differently.
Slice() assists in pulling parts of an array without modifying the original, while Splice() modifies the array itself by inserting, deleting, or substituting elements.
JavaScript has effective array manipulation functions through which developers can readily change and pick parts of arrays.
Although they look alike, they behave and are used differently. Let’s find out the difference in this post between slice() and splice() in terms of syntax, functionality, and usage.
What is the Slice Method?
The slice() function is employed to make a shallow copy of an array section without changing the original array. It is particularly handy when you want to pull out a part of an array but preserve the original.
Syntax
array.slice(startIndex, endIndex)- StartIndex: The point at which to start the slice (inclusive).
- EndIndex: The point at which to finish the slice (exclusive). It defaults to cutting to the end of the array.
Key Features
- Non-destructive: Nothing is changed about the original array.
- Returns shallow copy of requested portion.
Example
let arr = [1, 2, 3, 4, 5];
let slicedArr = arr.slice(1, 3); // [2, 3]
console.log(arr); // [1, 2, 3, 4, 5]In this example, the original array remains unchanged, and a new array [2, 3] is returned.
What is the Splice Method?
As opposed to slice(), splice() is a destructive function that alters the original array by deleting, inserting, or replacing elements. It’s ideal to use when you need to transform an array in place.
Syntax
array.splice(startIndex, deleteCount, item1, item2, .)- StartIndex: The position where modifications are to start.
- DeleteCount: The number of elements to delete from startIndex.
- Item1, item2, .: New items to add into the array.
Key Features
- Destructive: It updates the original array.
- Returns the deleted elements as an array.
Example
let arr = [1, 2, 3, 4, 5];Key Differences Between Slice and Splice
Now, let’s point out the major differences between slice() and splice()
| Features | Parameters | Destructive vs Non-Destructive | Purpose | Return Value |
|---|---|---|---|---|
| Slice() | slice() has two arguments: Start and End index (end is exclusive). | slice() does not change the original array. | slice() is to get a slice of the array. | slice() returns a new array containing the slice. |
| Splice() | splice() has three or more argumentsStart index, Number of elements to remove, and Optional elements to insert. | splice() changes the array itself by adding or deleting elements. | splice() changes the array by deleting, replacing, or adding elements. | splice() returns an array of deleted elements. |
Practical Use Cases
When to use slice()
- When you want to make a copy of a portion of the array without changing the original.
- When you are using immutable data structures and need to make sure that no changes happen to the original array.
When to use splice()
- When you want to change the original array, like delete or insert elements.
- For in-place replacing or updating elements.
Conclusion
In short, slice() and splice() are useful functions for manipulating arrays in JavaScript. While slice() assists you in making shallow copies of ranges of an array, splice() enables you to change the array by deleting or inserting elements.
Knowing when and how to utilize these techniques will make you write more effective and efficient JavaScript.
Key Takeaways
- Slice() removes a portion of an array without modifying the original array.
- Splice() modifies the original array by inserting, removing, or replacing elements.
- Slice() is not destructive, whereas splice() is destructive.
- Slice() returns a new array, whereas splice() returns the removed elements.
- Utilize slice() for array section copying and splice() for directly modifying the array.