list, Indexing & Slicing

list

Python's list is the equivalent of a JavaScript array. It's ordered, you can change it after creating it, and it can hold duplicate values.

JavaScript:

const fruits = ['apple', 'banana', 'cherry'];

Python:

fruits = ["apple", "banana", "cherry"]

Same idea — square brackets, comma-separated values. len() gives you the size:

len(fruits)   # 3

Indexing

Just like JS arrays, indexing starts at 0.

fruits[0]   # "apple"
fruits[1]   # "banana"

Python also supports negative indexing — a clean way to count from the end:

fruits[-1]   # "cherry" (last item)
fruits[-2]   # "banana" (second-last item)

In JS you'd reach for arr.at(-1) to get the same result; in Python -1 just works directly inside the brackets.

Slicing

Slicing lets you grab a sub-list using list[start:stop]. Just like range(), stop is not included.

fruits = ["apple", "banana", "cherry", "date"]

fruits[1:3]    # ["banana", "cherry"]
fruits[:2]     # ["apple", "banana"]   (start defaults to 0)
fruits[2:]     # ["cherry", "date"]    (stop defaults to the end)
fruits[:]      # ["apple", "banana", "cherry", "date"]  (a full copy)

JavaScript's closest equivalent is arr.slice(start, stop) — same start/stop behavior, just a method instead of bracket syntax.

A common trick — reverse a list with a slice:

fruits[::-1]   # ["date", "cherry", "banana", "apple"]