求最值:    var selections = $("#deliveryGridSalesOrGoods").datagrid('getRows');        var costPrice = '';        var ecPrice='';        if (selections != null && selections != '') {            for (var i = 0; i < selections.length; i++) {                costPrice += selections[i].ecPrice-selections[i].costPrice+',';            }        }        if(costPrice!=null){            costPrice = costPrice.substring(0, costPrice.lastIndexOf(","));        }        if (selections != null && selections != '') {            for (var i = 0; i < selections.length; i++) {                ecPrice += selections[i].ecPrice+',';            }        }        if(ecPrice!=null){            ecPrice = ecPrice.substring(0, ecPrice.lastIndexOf(","));        }                              var arry = new Array();      var newEc=costPrice.split(',');      var newecPrice=ecPrice.split(',');//      Number(value).toFixed(2);      var ecmin=Math.min.apply(null, newEc).toFixed(2);;//最小值      var ec_price=Math.min.apply(null, newecPrice).toFixed(2);;//最小值