How To Split Last 2 Digits Of Each Value In The String Array

I have an array:

last7day = ["", 20191219, 20191220, 20191221, 20191222, 20191223, 20191224, 20191225]

I want to split the last 2 digits of them. I tried last7day.split(-2) like slice command but couldn't succeed.

Desired output:

last7day = ["", 19, 20, 21...]

const last7day = ["", 20191219, 20191220, 20191221, 20191222, 20191223, 20191224, 20191225];
const arr = last7day.map(day => day.slice(-2));

console.log(arr);