js 计算金额是否小于总金额，大于是不能保存

function kpjejs(oInput){
    var result = 0;
    var vresult = "kpsq_kpzje";//开票总金额
    var wkje = "kpsq_dbhtwkpje"//合同未开票金额

    var xh = $("input[name='inputline_kpsqmx_num']").val();//总有条数
    xh = xh - 1;
    for(xh; xh >= 0; xh--){
        var dj = xh + "_kpsqmx_dj";//单价
        var sl = xh + "_kpsqmx_sl"//数量
        //var ckj = xh + "_kpsqmx_dbckj"//参考价

        var dbdj = $("input[name='" + dj + "']").val();
        var dbsl = $("input[name='" + sl + "']").val();
        //var dbckj = $("input[name='" + ckj + "']").val();
        var dbwkje = $("input[name='" + wkje + "']").val();
        
        if(typeof(dbdj)==="undefined"){
            dbdj = 0;
        }
        if(typeof(dbsl)==="undefined"){
            dbsl = 0;
        }

        if(xh >= 0){
            result = result + dbdj * dbsl;//总金额     
            $("input[name='" + vresult + "']").val(result);
            if(dbwkje < result){
                alert("开票金额不能大于合同未开票金额！请重新填写！");
                $("input[name='" + dj + "']").val("");
                $("input[name='" + sl + "']").val("");
                break;
            }
        }        
    }
}