Check out my program

var VisitorName = prompt("What's your name, Visitor?"); // "Bob"
      VisitorName += "!" // "Bob!"

alert("Hello " + VisitorName + "."); // "Hello Bob!."
var yes_no = prompt("Do you want to play a random number game? (Yes or No)");

if (yes_no.toLowerCase() === "yes") {
    alert("You need to choose two numbers so the program will generate a random number that lies in between");
    var StartingNum = prompt("Please input the Starting Number");
    var EndingNum = prompt("Please input the Ending number");
    StartingNum = parseInt(StartingNum);
    EndingNum = parseInt(EndingNum);
    if (StartingNum > EndingNum) {
        alert("Wrong Entry! " 
              + "The Starting Number must be less than the Ending Number. " 
              + "Please reload the page to rerun the program"); // What about 0 and 0 or 7 and 7?
    } else {
        document.write(Math.ceil( Math.random() * ( EndingNum - StartingNum )
                                 + StartingNum + " is a random number between " 
                                 + StartingNum + " and " + EndingNum + ".");
    }
} else if (yes_no.toLowerCase() === "no") {
    alert("Thank you for visiting!");
} else {
    alert("Wrong Entry! Please reload the page to try again.");
}