If it’s 2, you’re taking every other item. Step: The number of items from one included item to the next. Stop: The index of the first item to *not* include in the slice. Start: The index of the first item to include in the slice.

I find that the alliteration makes this easy to remember this way, and slice syntax also uses the same parameters as Python’s range() function. In Python, to get a slice of a list, you use the following syntax: arrayName. The same slicing syntax works in the same way for strings in both languages, but splicing doesn’t: both languages treat strings as immutable. replacing a slice), but possibly just inserting them between existing items.įor both of these features, JavaScript uses built-in methods of the Array class, while Python uses special syntax. Splicing is inserting a sequence of items in an array or list, possibly replacing a given section (i.e. When you use the syntax or method calls provided by the language to get a slice of an array, it’s basically a new array or list that’s shallow copy of that section of the original array/list. Usually it’s a contiguous section (but see the step parameter for an exception to that rule). Slicing and SplicingĪ slice is a section of an array or list. As we’ll see, there are some differences in the syntax used for splicing and splicing, but also a lot of similarities in how slicing and splicing work in the two languages. The differences between the structures they allow, such as that JavaScript arrays can be sparse, while Python’s lists don’t allow this, are beyond the scope of this post. They’re both loosely typed sequences of items, indexed by sequential integers starting at 0, with the ability to add or remove items at any point (in other words, they’re not a fixed length). Lists in Python and arrays in JavaScript are built-in data structures that are used for mostly equivalent things. This is intended as a map between the two languages, rather than a comparison of their strengths and weaknesses. This post covers some of the syntax and parameters for doing array or list slices and splices in Python and JavaScript - in other words, working with sections of lists or arrays, instead of the whole list/array - and some of the similarities and differences between them.

Js splice vs slice