RangeError: Maximum call stack size exceeded

for (var i = 0; i < unamelist.length; i++) {
        var uname = unamelist[i];
        console.log(uname);

        var Actionref = firebase.database().ref("Actionusers/" + mkey);
        var newData = {
            Actiontype: 3,
            status: true,
            Iscompleted: 0,
            username: uname.toLowerCase(),
            datetime: firebase.database.ServerValue.TIMESTAMP
        }

        Actionref.push(newData)
    }