let emailRE = /^[a-zA-Z0-9.!#$%&’*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*$/

let emails = ["fernando", "fernadno@", "fernando@test", "fernando@test.com", "valid_email123@host2.com", "a@1.com"]

emails.forEach( p => {
    let matches = p.match(emailRE)
    if(!matches) console.log(p, "INVALID EMAIL")
    else console.log(p, "is a valid email!")
})

/*
fernando INVALID EMAIL
fernadno@ INVALID EMAIL
fernando@test is a valid email!
fernando@test.com is a valid email!
valid_email123@host2.com is a valid email!
a@1.com is a valid email!
*/