Question

This is just an exercise I’m trying to complete. I was thinking in terms of creating an order form in the most basic way. I have a basic array with a list of guitars. I would have a user put a number in the first field and that number would reference an index in a array to put the array element in another text box. This is what I have at this point-

var gbrand = ('Jackson', 'BC Rich', 'Gibson', 'Fender', 'Dean', 'ESP', 'Fernandez');

function ordernum(gbrand)
{

    var order = document.order.perchnumb.value 

    if ( order != '' )
    {

      order = gbrand[index];
      document.order.instrum.value = order;

    }
}   

Answer 1

Using your code, I would say this should do the trick:

var gbrand = ['Jackson', 'BC Rich', 'Gibson', 'Fender', 'Dean', 'ESP', 'Fernandez'];

function ordernum(gbrand) {
    var orderId = document.order.perchnumb.value 

    if (orderId != '' && !isNaN(orderId)) {
      document.order.instrum.value = gbrand[orderId];
    }
}

If you leave your code like that, var gbrand will live in the global namespace, making it available to the function ordernum without actually passing it to the function as an argument.