Introduction to Google Form Mapping

code.gs

/**
 * Map function to get all the results from the database
 * this is specially useful if you're trying to access to
 * the questions and options as you may want to generate 
 * a report in your system...(not only the answers)
 *
 * I mainly did this because of the lack of good examples 
 * on the documentation, only through other github projects
 * and try and failure.
 *
 * I encourage you to use the official docs, but this may 
 * helps. https://developers.google.com/apps-script/reference/forms 
 */
function mapForm() {
    var form = FormApp.getActiveForm(); // You may have an active project where you're testing
    var items = form.getItems();

    var items_json = [];
    var accepted_types = ['TEXT', 'SCALE', 'MULTIPLE_CHOICE', 'CHECKBOX', 'GRID', 'LIST']; // Types of Questions (among many others)

    for (let i of items) {

        var id = type = title = null;
        var payload = {};
        let _gType = i.getType();
        Logger.log('/' + _gType + '/' + i); // Useful log with the type of the question

        if (i.getType() == "TEXT") {
            i.asTextItem();
        }

        if (i.getType() == "SCALE") { // https://developers.google.com/apps-script/reference/forms/scale-item
            var item = i.asScaleItem();
            var lower = item.getLowerBound();
            var upper = item.getUpperBound();
            var left_label = item.getLeftLabel();
            var right_label = item.getRightLabel();
            payload = {
                "lower": lower,
                "upper": upper,
                "left": left_label,
                "right": right_label
            };
        }

        if (i.getType() == "MULTIPLE_CHOICE" || i.getType() == "CHECKBOX") { // Those are really similiar https://developers.google.com/apps-script/reference/forms/multiple-choice-item
            var item = i.getType() ==  "MULTIPLE_CHOICE" ? i.asMultipleChoiceItem() : i.asCheckboxItem();

            var choices = item.getChoices();
            var options = [];
            for (var j = 0; j < choices.length; j++) {
                options.push({
                    "id": j,
                    "value": choices[j].getValue(),
                })
            }
            payload['choices'] = options;
        }

        if (i.getType() == "GRID") {
            var item = i.asGridItem();
            var columns = item.getColumns();
            var rows = item.getRows(); 
            payload = {
                "columns": columns,
                "rows": rows
            };
        }

        if (i.getType() == "LIST") {
            var item = i.asListItem();
            var choices = item.getChoices();
            var options = [];
            for (var j = 0; j < choices.length; j++) {
                options.push({
                    "id": j,
                    "value": choices[j].getValue(),
                })
            }
            payload['choices'] = options;
        }

        if (_gType != 'PAGE_BREAK') { // I didn't want to retrieve PAGE_BREAK 
            id = i.getId();
            type = i.getType();
            title = i.getTitle();

            items_json.push({
                "id": id,
                "type": type,
                "title": title,
                "payload": payload
            });
        }
    }
    Logger.log(Utilities.jsonStringify(items_json)); // This maybe not work with big JSON but you can send to your system by REST using https://developers.google.com/apps-script/reference/url-fetch/url-fetch-app
}