JSFiddle - React, Tailwind, and code Playground

JavaScript

document.write = function (str) {
    document.body.insertAdjacentHTML("beforeend", str);
}

var string = "1234567890"
var substr=string.substr(-8);
document.write(substr);
document.write('<br>');
var substr=string.substr(8);
document.write(substr);
document.write('<br>');
var substr=string.substr(0, 8);
document.write(substr);