List

Create Empty List

JS	Python
let arr = [];	arr = []

Create list with size:

let arr = new Array(5);

arr = [None] * 5

Add an item at the end

arr.push(1);

arr.append(1);

Add an item at the begin:

arr.unshift(2); arr.splice(0, 0, 2);

arr[:0]=[2] arr.insert(0,2)

Add items inside:

arr.splice(2,0,3,4);

arr[1:0]=[3]

Add 2 arrays:

let arr3 = arr1.concat(arr2);	arr3 = arr1 + arr2
arr = [...arr, ...otherArr];	arr = [*arr, *otherArr] arr.extend(otherArr)

Delete Items at the end

arr.pop();

arr.pop()

Delete items at the begin:

arr.splice(0,1);

arr[0:1]=[]

Delete items at the begin and return the deleted item

arr.shift();

arr.pop(0)

Delete Items inside (delete one item in index 1):

arr.splice(1,1);

arr[1:2]=[] arr.pop(1)

Initial values:

arr = new Array(5).fill(0);

arr = [0] * 5

Range:

[...Array(5).keys()].map(i=>i+5);

list(range(5,10)

Get first item:

arr[0]

arr[0]

Get last item:

arr.slice(-1)[0];

arr[-1]

Get first N items:

arr.slice(0, N);

arr[0: N]

Is list?

Array.isArray(arr)

isinstance(arr, list)

String to list:

arr = s.split(""); arr = [...s];

arr = list(s)

List to string

s = arr.join("");

s = "".join(arr)