How to change default "please fill out this field" in two field

Question

I would like two different messages in two field, for example, the username and password field that contain messages like "username cannot be blank" and "password cannot be blank". I only managed to change the message, but it is then the same for both fields. It's here

$(document).ready(function() {
var elements = document.getElementsByTagName("INPUT");
for (var i = 0; i < elements.length; i++) {
    elements[i].oninvalid = function(e) {
        e.target.setCustomValidity("");
        if (!e.target.validity.valid) {
            e.target.setCustomValidity("Username cannot be blank");
        }
    };
    elements[i].oninput = function(e) {
        e.target.setCustomValidity("");
    };
} })

Answer 1

sorry, some mistakes in my code. Try that, that works for me :

$(document).ready(function() {
var msg="";
var elements = document.getElementsByTagName("INPUT");

for (var i = 0; i < elements.length; i++) {
   elements[i].oninvalid =function(e) {
        if (!e.target.validity.valid) {
        switch(e.target.id){
            case 'password' : 
            e.target.setCustomValidity("Bad password");break;
            case 'username' : 
            e.target.setCustomValidity("Username cannot be blank");break;
        default : e.target.setCustomValidity("");break;

        }
       }
    };
   elements[i].oninput = function(e) {
        e.target.setCustomValidity(msg);
    };
} 
})

Answer 2

You can use this code.

   <input type="text"  required="" name="username" placeholder="Username" oninvalid="this.setCustomValidity('Username cannot be blank')">
   <input type="password"  required="" name="password" placeholder="Password" oninvalid="this.setCustomValidity('Password cannot be blank')">