var gridOptions = {
    defaultColDef: {
        filter: true
    },
    columnDefs: columnDefs,
    rowData: null,
    animateRows: true,
    isExternalFilterPresent: isExternalFilterPresent,
    doesExternalFilterPass: doesExternalFilterPass
};

var ageType = 'everyone';

    function isExternalFilterPresent() {
    // if ageType is not everyone, then we are filtering
    console.log('test');
    return ageType != 'everyone';
}

function doesExternalFilterPass(node) {

    console.log(node.data);
    switch (ageType) {
        case 'below30': return node.data.age < 30;
        case 'between30and50': return node.data.age >= 30 && node.data.age <= 50;
        case 'above50': return node.data.age > 50;
        case 'dateAfter2008': return asDate(node.data.date) > new
Date(2008,1,1);
        default: return true;
    }
}