Is there a way to search a field in a JSON array that can contain multiple values for a specific value?

I have an ajax query that returns results and should display them in an html table like the below:

<input type="button" value="Customer" onclick="SelectCustomer()">
<input type="button" value="Advisor" onclick="SelectAdvisor()">
<input type="button" value="Get Results" onclick="GetResults()">
<table id="results">
</table>

I'm wanting to filter this based on the affected area, so to show lists only items with a status of Open, and only impacting specific areas, such as Advisors, or Customers, etc. The current code I have to do this works in so far as it filters for Status, but I only get a blank return when I'm trying to filter the Affected Area field. I've been working with using JavaScript variables to contain information regarding whether a value has been selected or not, which is what I'm trying to filter against, however the filter script I have that shows only items with a Status value of Open doesn't seem to work for me if I have multiple values in the field.

var dResponse = [
    {"Reference": "123456","Status": "Open","AffectedArea": ["IT","Advisor"]}
    {"Reference": "654321","Status": "Closed","AffectedArea": ["Customer","IT"]}
    {"Reference": "567889","Status": "Open","AffectedArea": ["Advisor","Customer"]}
    {"Reference": "987654","Status": "Open","AffectedArea": ["Customer"]}
]
var custSelect = "Unselected";
var adviSelect = "Unselected";
var custfil = "";
var advifil = "";

function SelectCustomer(){
    if (custSelect == "Unselected") {
        custSelect = "Selected";
        adviSelect = "Unselected";
    } else {
        custSelect = "Unselected";
    }
}
function SelectAdvisor(){
    if (adviSelect == "Unselected") {
        adviSelect = "Selected";
        custSelect = "Unselected";
    } else {
        adviSelect = "Unselected";
    }
}

function GetResults() {
    var results = document.getElementById("results");
    var filResponse = dResponse.filter(function(item){
        return item.Status == "Open";
    })
    if (custSelect == "Selected"){
        FilterCust();
    }
    if (adviSelect ==" Selected"){
        FilterAdvi();
    }
    results.innerHTML += "<tr><td>Reference</td><td>Status</td><td>Affected Area</td></tr>";
    for(var obj in filResponse){
        results.innerHTML += "<tr><td>" + dResponse[obj].Reference + "</td><td>" + dResponse[obj].Status + "</td><td>" + dResponse[obj].AffectedArea + "</td></tr>";
    }
}

function FilterCust() {
 filResponse = dResponse.filter(function(item){
  return item.ImpactedArea == "Customer";
})
}
function FilterAdvi() {
 filResponse = dResponse.filter(function(item){
  return item.ImpactedArea == "Advisor";
})
}

Admittedly, I'm not sure how the JSON results display multiple values in the same field, however the results come from a REST query to a SharePoint list, and the script works from that, the above was to give an idea regarding what sort of data the JSON table has in it.