multi-select checkbox implementation

I'm trying to create a checkbox menu that outputs a NEW set of values (for searching a table) EACH time a checkbox menu item is checked OR unchecked.

I can get the table to filter on first checking an item, but not thereafter.

<input type="checkbox" id="cbox1" value="processes" onchange="searchFunction()">
<label for="cbox1">Processes and Roles </label>
</br>
<input type="checkbox" id="cbox2" value="knowledge" onchange="searchFunction()">
<label for="cbox2">Knowledge and Tools </label>


var table = $('#myTable').DataTable();
var searchObject = {};

function searchFunction(id) {
    if (document.getElementById('cbox1').checked) {
        searchObject.termOne = "processes";
    }
    if (document.getElementById('cbox2').checked) {
        searchObject.termTwo = "knowledge";
    }
    table.columns(2).search(searchObject.termOne + '|' + searchObject.termTwo, true, false).draw();
};