Getting list of IDs to the variable

Could anybody help me with the following. I need to create an array where I put IDs of all checked radio buttons. I have tried the following:

var checked = [];
$('.tsg input:checked').each(function() {
    var id = $(this).attr('id');
    checked = checked.push(id);

But it says

Uncaught TypeError: checked.push is not a function


checked.push(x) returns x.

By typing checked = checked.push(x), you’re replacing checked with x on the first iteration, after which checked is no longer an array and has no push method.

push modifies the array in place, there is no need for assignment.