JQuery increment maximum

JQuery increment maximum

I am learning jquery and have been given a little problem to solve and I cannot find the solution so hoping you can help me.

I am creating a small increment calculator which i have pasted together from bits and pieces I found online.

The problem I have is that i dont want it to go past 10, so if you press plus on teh calculator you cannot go any further. Also I dont want it to go past zero if you press minus, so no -1, -2 etc.

How would I achieve this?

The code i have is below.

many thanks!

Hayden

Price per item:<input name="basicPrice" value="50" class="input-text">
<br />
<input type="button" value="-" class="minus">
<input name="quantity" id="quantity" type="number" value="1"  class="input-text">
<input type="button" value="+" class="plus">
<br />Money must pay:
<span class="newprice">20</span>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script>
function calculate(){
    var basicPrice = parseInt($(":input[name='basicPrice']").val());
    var quantity = parseInt($(":input[name='quantity']").val());
    var total = basicPrice * quantity;
    $(".newprice").text(total);
}
function changeQuantity(num){
    $(":input[name='quantity']").val( parseInt($(":input[name='quantity']").val())+num);
}
$().ready(function(){
    calculate();
    $(".minus").click(function(){
        changeQuantity(-1);
        calculate();
    });
    $(".plus").click(function(){
        changeQuantity(1);
        calculate();
    });
   
    $(":input[name='quantity']").keyup(function(e){
        if (e.keyCode == 38) changeQuantity(1);
        if (e.keyCode == 40) changeQuantity(-1);
        calculate();
    });
   
    var quantity = document.getElementById("quantity");
    quantity.addEventListener("input", function(e) {
        calculate();
    });
});</script>