Passing array from view to controller using Ajax but, on action, array shows as empty

  jQuery.ajaxSettings.traditional = true;

$("#btn").click(function () {
            debugger
             arry = [];
                $.ajax({
                type: "Post",
                url: "/Main/CheckBoxes",
                data: { Values:["48","47","46"]},//just edit this line
                success: function () {
                    alert("array: " + arry.join(', '));
                },
                error: function () {
                    alert("error");
                }
            })


        });

Your code has some issues regarding how you are sending the data! What is your expectation when you execute this expression arr["48","47","46"] ????? That is going to give you undefined and that is what you are trying to send!

There are two ways to fix your code. You can send the array in the request body. For this, you need create a JSON string from the array and send that as the data property while explicitly specifying the request content-type header value as "application/json". You may use the JSON.stringify method to get the JSON string of your js array.

Also, make sure you are making the call to the correct action method. In your question you shared the array action method code, but in your client side script you were trying to call a different action method(`Checkboxes)!

This should work.

var arry = ["48", "47", "46"];
var url = "@Url.Action("array", "Main")";  // Update your real url here
// If your script is inside the razor view, you can us Url.Action (c#) method

$.ajax({
    type: "Post",
    url: url ,
    data: JSON.stringify(arry),
    contentType: "application/json",
    success: function(r) {
        alert("Success");
        console.log(r);
    },
    error: function() {
        alert("error");
    }
});

Another option is to send a javascript object with Values property (which has the array as the value of it) as the data property value of the $.ajax call. Now the request content-type header will be application/x-www-form-urlencoded; and the array will be sent as FormData in the request.

var arry = ["48", "47", "46"];

$.ajax({
    type: "Post",
    url: "/Main/array",
    data: { Values: arry },
    success: function(r) {
        console.log(r);
    },
    error: function() {
        alert("error");
    }
});