function myFunction() {
var rate = document.getElementById("payrate").value;
var hours = document.getElementById("hours").value;
var salary;
salary = rate * hours;
if (hours == ' ') {
    alert("Fill hours");
}
else if (payrate == ' ') {
    alert("Fill payrate");
}
if (salary < 20000) {
    salary = "The salary is too little";
} else if(salary > 20000 && salary < 25000){
    salary = "Let's negotiate";
} else {
    salary = "This good salary";
}
document.getElementById("demo").innerHTML = salary;
}