How to return value from array to the function

if it is a synchronous call, then try this, your var test_values = []; should be outside if (status == google.maps.DistanceMatrixStatus.OK) condition. And most probably insideif (status == google.maps.DistanceMatrixStatus.OK) is not executing

also google.maps.DistanceMatrixStatus.OK is asynchronous so better to return value inside if(google.maps.DistanceMatrixStatus.OK)

So try this

   function initMap() {
     console.log(getDistanceandTime(srcRouteAddress.lat,srcRouteAddress.lng,destRouteAddress.lat,destRouteAddress.lng));

    function getDistanceandTime(lat1,lon1,lat2,lon2){
    var origin = {lat: parseFloat(lat1), lng: parseFloat(lon1)};
    var destination = {lat: parseFloat(lat2), lng: parseFloat(lon2)};
    var service = new google.maps.DistanceMatrixService;
    //var test = [];
    service.getDistanceMatrix({
        origins: [origin],
        destinations: [destination],
        travelMode: google.maps.TravelMode.DRIVING
    }, function (response, status) {
                         var test_values = [];
        if (status == google.maps.DistanceMatrixStatus.OK) {

            var originList = response.originAddresses;
            for (var i = 0; i < originList.length; i++) {
                var results = response.rows[i].elements;
                for (var j = 0; j < results.length; j++) {
                    var test = results[j].distance.text + ' in ' + results[j].duration.text;
                    test_values.push(test);
                    console.log(test_values);
                }
            }
            return test_values;
        }

    });
  }

 }

Try this..

var test_values = []; // global variable
function initMap() {
    // your code here
}

function showLatLng(){
    console.log(test_values); // will output the content
}

Javascript runs on the UI thread; if your code waits for the server to reply, the browser must remain frozen. Ajax jquery async return value