Prompt function against HTML doc loading in JS [duplicate]

let ans=document.querySelector("p")
let text;
text=Math.floor(Math.random()*100+1);

flag=true;
while(flag===true){
    let guessed=parseInt(prompt("Guess the number?"));
    if (guessed===text){
        ans.textContent="Congratulations! U guessed it right!";
        flag=false;
    }
    else if (guessed>text){
        ans.textContent="Guess lower!";
    }
    else if (guessed<text){
        ans.textContent="Guess higher!";
    }
    
}

How do i prompt the user using prompt() function after the HTML has completely loaded?

The above code will not load complete html and prompts the user immediately as you reload the page.