dropdown change the input value

by Akram kamal

HTML

<div class="row-fluid">
                                    <div class="span3">
                                        <label for="sales_srp">SRP</label>
                                        <input class="form-control input sales_srp" name="sales_srp" id="sales_srp" required="true" type="text" data-toggle="tooltip" data-placement="top" title="Type the amount of SRP here"  />
                                    </div>   
                                    <div class="span3">
                                        <label for="sales_lcp_rate">LCP Rate</label>
                                        <input class="form-control input sales_lcp_rate" name="sales_lcp_rate" id="sales_lcp_rate" required="true" type="text" data-toggle="tooltip" data-placement="top" title="Type the amount of LCP rate here" />
                                    </div>    
                                    <div class="span3">
                                        <label for="sales_lcp">List Cash Price (LCP)</label>
                                        <input class="form-control input sales_lcp" name="sales_lcp" id="sales_lcp" required="true" type="text" readonly="true" data-toggle="tooltip" data-placement="top" title="Click this field to show the total LCP"  />
                                    </div>      
                                    <div class="span3">
                                        <label for="sales_downpayment">Down Payment (DP)</label>
                                        <input class="form-control input sales_downpayment" name="sales_downpayment" id="sales_downpayment" required="true" type="text" data-toggle="tooltip" data-placement="top" title="Type the amount of Downpayment here"  />
                                    </div>                                                                                                                                       
                                </div>                                
                      ...

JavaScript

$(document).ready(function(){
    
    function calculate(){
        var sales_srp = parseInt($('#sales_srp').val());
    var sales_lcp_rate = $('#sales_lcp_rate').val();
    var sales_lcp = parseInt($('#sales_lcp').val());
    var sales_downpayment = parseInt($('#sales_downpayment').val());
    var sales_amtbf = parseInt($('#sales_amtbf').val());
    var sales_interestrate = parseInt($('#sales_interestrate').val());
    var sales_promisorrynote = parseInt($('#sales_promisorrynote').val());
    var sales_terms = $('#sales_terms').val();
    var sales_mi = parseInt($('#sales_mi').val());
    var sales_tcp = parseInt($('#sales_tcp').val());
    var sales_addon_ppd = parseInt($('#sales_addon_ppd').val());


    $('#sales_lcp').val(Math.round(sales_srp * sales_lcp_rate));
    $('#sales_amtbf').val(Math.round(sales_lcp - sales_downpayment));
    $('#sales_mi').val(Math.round((sales_promisorrynote / sales_terms) + sales_addon_ppd));
    $('#sales_tcp').val(Math.round(sales_promisorrynote + sales_downpayment));
    $('#sales_interestrate').val((sales_terms * 0.02 )+1);
    $('#sales_promisorrynote').val(Math.round(sales_amtbf * sales_interestrate));
    }

$('#sales_srp, #sales_lcp_rate, #sales_lcp, #sales_downpayment, #sales_amtbf, #sales_interestrate, #sales_promisorrynote,  #sales_mi, #sales_tcp, #sales_addon_ppd').on('input',calculate);
$('#sales_terms').on('change', calculate);
});