In this post we'll master the slice method by example, exploring 8 different ways it can be used.Ĭaution: The slice method is not to be confused with the splice method, which modifies an array in place.

Thus it provides a key building block for writing functional JavaScript. The slice method provides a mechanism for creating a shallow copy of a subset of a list, without modifying the original list. The JavaScript array slice method fits both of these criteria. Functional programming requires pure functions, functions that do not cause side effects or modify their input data.Functional programming, particularly higher level functions, works heavily with lists of data.Negative indices are also supported and will be counted from the end.The JavaScript array slice method is one of the most powerful and commonly used built-ins in the JavaScript language.Īnd with the rise of React and other functionally oriented JavaScript practices, it is becoming even more important, for 2 key reasons:

It takes two parameters, startIndex (inclusive) and endIndex (exclusive), which can be omitted to slice from the start index to the last element of the array. The `slice` method in JavaScript is a useful tool for extracting portions of an array without modifying the original. Let newArray = array.slice(-3, -1) // Slice from the third last element to the last element. Keep in mind that if you provide negative indices, they’ll be counted from the end: Let newArray = array.slice(2) // Slicing from index 2 (inclusive) to the end of the array In that case, it will slice the array from startIndex to the last element of the array. Slice from index 1 (inclusive) to index 4 (exclusive)Ĭonsole.log(newArray) // Output: Ĭonsole.log(array) // Output:, Original array is not modified Here’s how to use the `slice` method in JavaScript: It creates a new array that has elements starting from the specified begin index (inclusive) up to, but not including, the end index (exclusive). The Array `slice` method in JavaScript is used to extract a portion of an array, without modifying the original array. In this blog post we’ll explore how to use this useful method with examples.

Negative indices are also supported and they’ll be counted from the end. You can also omit the endIndex and it will slice from startIndex to the last element of the array. The `slice` method in JavaScript is a powerful tool for extracting portions of an array without modifying the original.

Array slice in javascript