!DOCTYPE html
html lang=en
head
meta charset=UTF-8
titleServer Processing...title

style
    body{
        margin0;
        background#000;
        font-family Consolas, monospace;
        color#00ff9c;
    }

    .terminal{
        padding25px;
        font-size16px;
        line-height1.6;
        white-spacepre-wrap;
    }

    .cursor{
        displayinline-block;
        width10px;
        background#00ff9c;
        margin-left5px;
        animation blink 1s infinite;
    }

    @keyframes blink{
        0%{opacity0}
        50%{opacity1}
        100%{opacity0}
    }
style
head

body

div class=terminal id=terminaldiv

script
const lines = [
[BOOT] Initializing secure environment...,
[OK] Loading system modules...,
[OK] Connecting to main server...,
[OK] Establishing encrypted channel...,
[INFO] Checking server resources...,
[INFO] Allocating memory...,
[INFO] Starting background workers...,
[INFO] Processing request...,
[INFO] Running verification checks...,
[INFO] Syncing data packets...,
[INFO] Waiting for server response...,
[INFO] Processing still running...,
[INFO] Please do not close this window...
];

let term = document.getElementById(terminal);
let i = 0;

function typeLine(){
    if(i  lines.length){
        let line = document.createElement(div);
        term.appendChild(line);

        let text = lines[i];
        let charIndex = 0;

        let typer = setInterval(()={
            line.textContent += text.charAt(charIndex);
            charIndex++;
            if(charIndex = text.length){
                clearInterval(typer);
                i++;
                setTimeout(typeLine, 500);
            }
        }, 25);
    } else {
        loopMessages();
    }
}

function loopMessages(){
    const msgs = [
        [INFO] Server still processing...,
        [INFO] Optimizing data...,
        [INFO] Finalizing tasks...,
        [INFO] Processing...
    ];

    setInterval(()={
        let line = document.createElement(div);
        line.textContent = msgs[Math.floor(Math.random()msgs.length)];
        term.appendChild(line);
        window.scrollTo(0,document.body.scrollHeight);
    }, 2000);
}

typeLine();
script

body
html