jQuery Grid Plugin - jqGrid

jQuery("#listSales").jqGrid({
        url:'../json/sales?horizon=1',
        datatype: "json",
        height: 450,
        width: 980,
        colNames:['ID', 'Sub-Account', 'Account', 'Partner', 'Admin', 'Transaction ID', 'Transaction date', 'Name', 'Email', 'Amount', 'Cur', 'Vocher', 'Received', 'Mobile', 'Package Id', 'Package Name', 'Expiration', 'User', 'User Mac', 'NasID', 'Router MAC'],
        colModel:[
            {name:'rowID',hidden: true},
            {name:'account',index:'account', width:60},
            {name:'affiliate',index:'affiliate', width:60},
            {name:'partner',hidden: true},
            {name:'admin',hidden: true},
            {name:'transid',index:'transid', width:110},
            {name:'transdate',index:'transdate', width:90},
            {name:'name',index:'name', width:100},
            {name:'email',index:'email', width:150},
            {name:'amountpaid',index:'amountpaid', width:40, sorttype:'int', formatter: 'number'},
            {name:'currency',index:'currency', width:25},
            {name:'voucher',index:'voucher', width:10,formatter:'checkbox'},
            {name:'youoweus',index:'youoweus', width:10,formatter:'checkbox'},
            {name:'mobile',hidden: true},
            {name:'timeid',hidden: true},
            {name:'package',hidden: true},
            {name:'expiration',hidden: true},
            {name:'userid',hidden: true},
            {name:'mac',hidden: true},
            {name:'nasid',hidden: true},
            {name:'routermac',hidden: true},
        ],
        rowNum:20,
        loadonce:true,
        scroll: 1,
        mtype: "GET",
        rownumbers: true,
        rownumWidth: 30,
        gridview: true,
        pager: '#pager',
        sortname: 'transdate',
        ignoreCase: true,
        loadui: "block",
        viewrecords: true,
        sortorder: "desc",
        caption: "<?= $this->contentHeader ?>",
        footerrow : true,
        userDataOnFooter : true,
        altRows : true,
        loadComplete: function() {
            var footerData = new sumAmountPaid();
            var footerRow = jQuery("#listSales").footerData('set',footerData, false);
        }
    });
    jQuery("#listSales").jqGrid('filterToolbar',{stringResult:true,searchOnEnter:false,defaultSearch:"cn"});

function sumAmountPaid() {
        // read grid data
        var thedata = jQuery("#listSales").getGridParam('data');
        // read filters
        var postData = jQuery("#listSales").getPostData();
        // convert POST filters into usuable REGEX format – but only if there is a search
        if(postData._search) {
            var filterObj = jQuery.parseJSON(postData.filters);
            // extract group Operator
            var groupOp = filterObj.groupOp;
            //construct REGEX filter array
            var filterArray = new Array();
            jQuery.each(filterObj.rules,function(theKey,theValue) {
                // the "i" is required for the jqGrid setting ignoreCase: true,
                // remove it for and ignoreCase: false type jqGrids
                switch (theValue.op) {
                    case 'cn':
                        filterArray[theValue.field] = new RegExp(theValue.data, "i");
                        break;
                    case 'bw':
                        filterArray[theValue.field] = new RegExp('^' + theValue.data, "i");
                        break;
                    case 'ew':
                        filterArray[theValue.field] = new RegExp(theValue.data + '$', "i");
                        break;
                    case 'eq':
                        filterArray[theValue.field] = new RegExp('^' + theValue.data + '$', "i");
                        break;
                    case 'nc':
                        filterArray[theValue.field] = new RegExp('^(?:(?!' + theValue.data +').)+$', "i");
                        break;
                    case 'bn':
                        filterArray[theValue.field] = new RegExp('^(?:(?!' + theValue.data +').)$', "i");
                        break;
                    case 'en':
                        filterArray[theValue.field] = new RegExp('(?:(?!' + theValue.data +').)$', "i");
                        break;
                    case 'ne':
                        filterArray[theValue.field] = new RegExp('^(?:(?!' + theValue.data +').)$', "i");
                        break;
                }
            })
        }
        // initialise values
        var thesum = 0;
        var thecurrency="n/a";
        // loop over grid data
        for(var i=0;i < thedata.length; i++) {
            // add vlaues if there is no search or if the search criteria meet the data
            if (!(postData._search) || matchFilter(thedata[i],filterArray,groupOp)) {
                //make sure data is value and not string – then add
                thesum += parseFloat(thedata[i].amountpaid);
                // the values I add are currencies, only add if it is the same currency, otherwise stop adding – simialr applies for anything with a ubit of measure (UOM)  and if the constance of the UOM caanot be guranteed)
                if (thecurrency == "n/a") {
                    thecurrency = thedata[i].currency;
                } else {
                    // give some standard values, if the UOM is not the same throughout
                    if (thecurrency != thedata[i].currency) {
                        this.name = 'Total:';
                        this.amountpaid = 'n/a';
                        this.currency = 'n/a';
                        return;
                    }
                }
            }
        }
        this.name = 'Total:';
        this.currency = thecurrency;
        // format and round the number
        if(thesum == 0) {
            this.amountpaid = '0.00';
        } else {
            this.amountpaid = roundNumber(thesum, 2);
        }
    }

    function roundNumber(rnum, rlength) { // Arguments: number to round, number of decimal places
        var newnumber = Math.round(rnum*Math.pow(10,rlength))/Math.pow(10,rlength);
        return newnumber;
    }
    function matchFilter(data, filterArray, groupOp) {
        var valid = true;
        // read filter array
        for (var theKey in filterArray) {
            //compare data field with filter
            if (data[theKey].search(filterArray[theKey]) != -1) {
                //if it is an OR, one match is enough
                if(groupOp == "OR") {
                    return true;
                }
                valid = true;
            } else {
                //if it is an AND, one fail is enough
                if(groupOp == "AND") {
                    return false;
                }
                valid = false;
            }
        }
        return valid;
    }