How to make an alert window show after the right words has been inputted In the box and the disabled button can be clicked

Question

<label for="fname">code</label>
<input type="text" id="v" name="firstname" placeholder="code" onkeyup="f()" required>
<button id="btn1" onclick="f()" disabled>Try it</button>
function f() {
var i;
var a = [ "Q", 1];
var p = document.getElementById("v").value;
var c = document.getElementById("btn1");
c.disabled = true;
for(var i = 0; i < a.length; i++) {
if (a[i] == p) {
c.disabled = false;
document.getElementById("no").innerHTML = "Congrats" + m;
}
}
}

Answer 1

i guess this:
<label for="fname">code</label>
<input type="text" id="code" name="firstname" placeholder="code" onkeyup="f()" required>
<button id="btn1" onclick="f()" disabled>Try it</button>
function f() {
var answers = [ "Q", 1];
var input = document.getElementById("code").value;
var btn = document.getElementById("btn1");
for(var i=0; i<answers.length; i++) {
if (answers[i] == input) {
btn.disabled = false;
alert("Congrats");
}
}
}