Please show your love and support by sharing this post. 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: Instead of passing the end index value as arrayLength, pass end index as n.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. More on JavaScript: What Are JavaScript Algorithms and Data Structures?Ģ. Var copiedNumbers = numbers.slice(0, numbers.length) īy default, the start index is 0 and the end index is the length of the array.

Use Array Slice to Copy an Array var numbers = So, we can have a -1 point to last element.īelow are some common ways you can use the array slice method in JavaScript.ġ. We can also give a negative value for the start and end index, which indicates an offset from the end of the array.The slice doesn’t affect the source array from which we are performing slice.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. By default the start is 0 and end is array.length According to the MDN Web Docs documentation, the Array.Both start and end is an optional argument.Here’s a brief refresher on the slice method:

Node js array slice