Util.js

// Assumes n is a Number.
function isInt_(n) {
    return n % 1 === 0;
}

function base64EncodeSafe_(string) {
    var encoded = Utilities.base64EncodeWebSafe(string);
    return encoded.replace(/=/g, "");
}

function removeTrailingSlash_(string) {
    const length = string.length;
    if (string.charAt(length - 1) === '/') {
        // Remove trailing slash
        return string.substr(0, length - 1);
    } else {
        return string;
    }
}

function getObjectFromResponse_(response) {
    return JSON.parse(response.getContentText());
}

function checkForError_(responseObj) {
    if (responseObj["error"]) {
        throw new Error(responseObj["error"]["message"]);
    }
}

function getIdFromPath_(path) {
    return path.split("/").pop();
}

function addAll_(array, itemsToAdd) {
    for (var i = 0; i < itemsToAdd.length; i++) {
        var item = itemsToAdd[i];
        array.push(item);
    }
}