Answer 1

I see, you try to check if the sq root contains a "."

How about this?

// make sure it's a string
let s = Math.sqrt(txt).toString();
// use includes()
if (!s.includes("."))

Answer 2

What are we supposed to input?

Answer 3

"!" means "not", it negates the boolean:

! true is false

Answer 4

// Your Mom , Hope this code helps you

function morseCode() {

for (var i = 0; i < txt.length; i++) {
switch (txt.charAt(i)) {
case "a":
morse += " •-";
break;
case "b":
morse += " -•••";
break;
case "c":
morse += " -•-•";
break;
default:
morse += "";
}
}

console.log(morse);
}