If for some reason you would rather have more elements in the left array than the right one, then you can simply substitute Math.floor() with Math.ceil() like so:Ĭonst middle = Math.ceil(arr.length / 2) Ĭonsole.log(left) // output: Using Math.floor() would make the left array have less elements than the right array. arr.length).Īs you can see in the example code above, an array with odd number of elements would yield unbalanced left / right arrays. Please note that if you omit the second argument to the slice() method (such as in the ' right' array in the code above), it extracts all elements of the array starting from the specified index till the end of the array (i.e. For example:Ĭonst middle = Math.floor(arr.length / 2) Ĭonsole.log(right) // output: Ĭonsole.log(arr) // output: The function returns a new array containing the copied values.The best way to split an array into two halves in JavaScript is by using the () method, because it returns a portion of the array without modifying the original array (i.e.

If end is greater than the sequence length, slice extracts through to the end of the sequence.

For example, slice(1,-1) extracts the first element through the second-to-last element in the sequence.

If negative, it extracts until the end of the sequence.

If not supplied, it extracts to the end of the sequence.

end (optional) : The ending index of the copied array.

If start is greater than the index range of the sequence, an empty array is returned.

For example, slice(-2) extracts the last two elements in the sequence.

If negative, it indicates an offset from the end of the sequence.If not supplied, it starts from index 0.start (optional): The starting index of the copied array.

The slice() method takes the following parameters: It saves this copied portion into a new array but does not modify the original array.

The slice() method in JavaScript returns a shallow copy of an array’s selected portion.

Node js array slice