List pass through ajax in ASP.Net MVC

I want to pass list through AJAX. How can I do this and assign value on runtime. I am doing it, but it pass null value. Here is my code.

JQuery:

for (var i = 0; i < 5; i++) {
    aabc += { id: i, color: 'Level' + i } + ",";
}
var str2 = aabc.replace(/,$/, " ")
JSONString3 = [str2];
$.ajax({
    url: '@Url.Action("test123", "ConfigurableTradeLane")',
    type: 'POST',
    contentType: 'application/json; charset=utf-8',
    data: JSON.stringify(JSONString3),
    success: function (data) {
       //alert("success");
    },
    error: function (jqXHR, exception) {
        alert('Error message.');
    }
});

Controller:

public void test123(List<TradelaneDetailViewModel> viewmodel)
        {
            //nothing
        }

It send “item value is null”. Please help me.

Answers:

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Method 1

Assuming TradelaneDetailViewModel contains properties id and color, then the script needs to be

var items = [];
for (var i = 0; i < 5; i++) {
    items.push({ id: i, color: 'Level' + i });
}
$.ajax({
    url: '@Url.Action("test123", "ConfigurableTradeLane")',
    type: 'POST',
    contentType: 'application/json; charset=utf-8',
    data: JSON.stringify({ viewmodel: items }),
    success: function (data) {
       //alert("success");
    },
    error: function (jqXHR, exception) {
        alert('Error message.');
    }
});

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