Question

I have 1 select, 2 text inputs & some JSON data in a form:

• select input: List of Suppliers
• text input 1: Net Amount
• text input 2: Gross Amount
• JSON Data:contains the rates of various suppliers as JSON in supplier_tax_rates

I am calculating Gross Amount something like this(pseudo code):

grossAmount = NetAmount + ((currently_selected_supplier.tax_percentage_charged / 100) * netAmount)

Here is the complete code:
Calculate total after retriveing tax rate from JSON

Now, this should work but it doesn’t. I get NaN(not a number), means something is wrong. But I have trouble find where.

• JSfiddle

Answer 1

You have multiple problems in your code. Here is the correct version:

var taxRates = $.parseJSON(supplier_tax_rates);

var getTaxRate = function(id) {
    for (var i in taxRates) {            // correct loop definition
        if (taxRates[i].id == id) {      // check you get id correctly
            return taxRates[i].tax_percentage_charged;   // instead of 'rate'
        }
    }
};

$('#PurchaseNetAmount').on('change', function(event) {
    var taxRatesId = $('#PurchaseSupplierId').val();
    var netAmount = parseFloat(this.value);
    var grossAmount = netAmount + ((getTaxRate(taxRatesId) / 100) * netAmount);
    $('#PurchaseGrossAmount').val(grossAmount);
});

DEMO: http://jsfiddle.net/A9vmg/18/