gistfile1.js

var userNum, computerNum, message;
userNum = Number(prompt("Pick a number between 1 and 10!"));
computerNum = (Math.floor(Math.random() * 10)) + 1;

//sanitize input then Check guess
if (userNum >= 11) {
    message = "Too high of a number, please refresh and pick again!";
} else if (isNaN(userNum)) {
    message = "This is not a number, please refresh and pick again!";
} else if (userNum === computerNum) {
    message = "You are correct sir!";
} else if (userNum + 1 === computerNum || userNum - 1 === computerNum) {
    message = "So close! It was " + computerNum;
} else {
    message = "Sorry, it was " + computerNum;
}

alert(message);