test.js

async function addComment() {

    var id = Math.random().toString(36).substring(2); // random id

    var userName = await getUserNames();

    // create comment object
    var comment = {
        comment: "",
        author: userName,
        timestamp: Date.now(),
        id: id,
    };

    var range = await getSelectionRange();
    TXTextControl.select(range.start, 0);

    // insert start target
    TXTextControl.documentTargets.add("txcs_" + id, dt => {
        dt.setName(JSON.stringify(comment));
        dt.setDeleteable(false);

        TXTextControl.select(range.end, 0);

        // insert end target
        TXTextControl.documentTargets.add("txce_" + id, endTarget => {

            _activeComment = id;
            refreshComments();
        });
    });
}