Javascript Increment by more than 1?

Question

Here's my script :

//event handler for item quantity in shopping cart
    function itemQuantityHandler(p, a) {
        //get current quantity from cart
        var filter = /(\w+)::(\w+)/.exec(p.id);
        var cart_item = cart[filter[1]][filter[2]];
        var v = cart_item.quantity;


        //add one
        if (a.indexOf('add') != -1) {
            if(v < settings.productBuyLimit) v++;
        }
        //substract one
        if (a.indexOf('subtract') != -1) {
            if (v > 1) v--;

        }
        //update quantity in shopping cart
        $(p).find('.item-quantity').text(v);
        //save new quantity to cart
        cart_item.quantity = v;
        //update price for item
      $(p).find('.item-price').text((cart_item.price*v).toFixed(settings.numberPrecision));
        //update total counters 
        countCartTotal();
    }

What I need is to increase "v" (cart_item.quantity) by more than one. Here, it's using "v++"...but it's only increasing by 1. How can I change this to make it increase by 4 everytime I click on the plus icon?

I tried

v++ +4

But it's not working.

Thank you!

Answer 1

Use a compound assignment operator:

v += 4;