if (typeof (EASI) == "undefined")
{ EASI = {}; }
EASI._construct = function () {
    //filter subgrid and refresh function
    this.FilterSubgridandRefresh = function (subgridname, stringArrayOfCondtionsToAdd, removeExistingConditionsBool) {
        try {
            window.setTimeout(function () {

                var subgrid = document.getElementById(subgridname);

                if (subgrid == undefined || subgrid == null) 
                {
                    throw "EASI SubGridFetchBuilder...subgrid not ready...contact [email protected]";
                }

                var oldFetch = $("#" + subgridname).find("#effectiveFetchXml").attr("value");
                if (oldFetch == undefined) {
                    //we have to refresh the grid now because it was in a tab that was collapsed so it hasn't run yet
                    subgrid.control.refresh();
                    //re-run this operation
                    setTimeout(function () {
                        EASI.FilterSubgridandRefresh(subgridname, stringArrayOfCondtionsToAdd, removeExistingConditionsBool);
                    }, 1000);
                }
                else {
                    var html_fetch = $("<div>" + oldFetch + "</div>");
                    if (removeExistingConditionsBool)//remove the existing conditions
                        html_fetch.find("condition[operator!='']").remove();
                    for (var i in stringArrayOfCondtionsToAdd) {
                        var cond = $(stringArrayOfCondtionsToAdd[i]);
                        html_fetch.find("filter").append(cond);
                    }
                    var newFetch = html_fetch.html();
                    subgrid.control.SetParameter("fetchXml", newFetch);
                    subgrid.control.refresh();
                }
            }, 1000);
        }
        catch (err) {
            alert("Error in subgrid refresh\r\n" + err.message);

        }
    }
    //get crm field value function
    this.GetFieldValue = function (fieldlogicalname) {
        if (typeof (Xrm) == "undefined")
            Xrm = window.parent.Xrm;
        var atype = Xrm.Page.getControl(fieldlogicalname).getAttribute().getAttributeType();

        if (atype == this.CRM.type_optionset) {
            return this.GetPicklistSelectedValue(fieldlogicalname);
        }
        else if (atype == this.CRM.type_lookup) {
            return this.GetLookupId(fieldlogicalname);
        }
        else {
            return Xrm.Page.getControl(fieldlogicalname).getAttribute().getValue();
        }
    }

}

EASI._construct();

/*here is an implementation example*/
function filterGrid_Load() {

    var oid = $("#opportunityid").attr("value");
    var configno = EASI.GetFieldValue("easi_configurationno");
    FilterSubGrid_OppDetailSubgrid("DoNotRemove_options_subgrid", oid, configno, 101);
    function FilterSubGrid_OppDetailSubgrid(subgridname, oppid, configno, lineitemtype) {
        try {
            var newcond1 = "<condition attribute=\"easi_configurationno\" operator=\"eq\" value=\"" + configno + "\" />";
            var newcond2 = "<condition attribute=\"opportunityid\" operator=\"eq\" value=\"" + oppid + "\" />";
            var newcond3 = "<condition attribute=\"easi_lineitemtype\" operator=\"eq\" value=\"" + lineitemtype + "\" />";
            var newcond4 = "<condition attribute=\"easi_removeoption\" operator=\"ne\" value=\"" + 1 + "\" />";
            var condArray = new Array(newcond1, newcond2, newcond3, newcond4);
            EASI.FilterSubgridandRefresh(subgridname, condArray, true);
        }
        catch (err) {
            alert("error filtering subgrid: " + err.message);
        }
    }
}

Filters a dynamics CRM 2011 subgrid...implementation example included at bottom

Dynamics CRM 2011 Filter Subgrid and Refresh

filter

JavaScript