Google Apps Script:
Parsing a date from a string

How to:

In Google Apps Script, which is based on JavaScript, you have several approaches to parse a date from a string. Below are examples using both native JavaScript methods and Google Apps Script utilities.

Using new Date() constructor:

The simplest way to parse a string into a date in Google Apps Script is using the Date object’s constructor. However, it requires the date string to be in a format recognized by the Date.parse() method (e.g., YYYY-MM-DD).

const dateString = '2023-04-01';
const dateObject = new Date(dateString);
Logger.log(dateObject); // Logs Sat Apr 01 2023 00:00:00 GMT+0000 (UTC)

Using Utilities.parseDate():

For more flexibility, particularly with custom date formats, Google Apps Script provides Utilities.parseDate(). This method allows you to specify the date format, timezone, and locale.

const dateString = '01-04-2023'; // DD-MM-YYYY
const format = 'dd-MM-yyyy';
const timezone = Session.getScriptTimeZone();
const dateObject = Utilities.parseDate(dateString, timezone, format);
Logger.log(dateObject); // Logs Sat Apr 01 2023 00:00:00 GMT+0000 (UTC) depending on the script's timezone

Note: While Utilities.parseDate() offers more control, its behavior can vary based on the script’s timezone, so it’s crucial to explicitly specify the timezone if your application handles dates across multiple regions.

Deep Dive

Date parsing in programming languages has historically been fraught with challenges, mainly due to the variety of date formats and the complexities of time zones. Google Apps Script’s approach, primarily derived from JavaScript, aims to simplify this by offering both the straightforward Date object and the more versatile Utilities.parseDate() function. However, each method has its limitations; for instance, relying on the Date constructor with strings leads to inconsistencies across different environments due to differing interpretations of date formats. On the other hand, Utilities.parseDate() requires a clearer understanding of the format, timezone, and locale, making it slightly more complex but more reliable for specific needs.

Alternative libraries or services, like Moment.js (now recommending Luxon for new projects), provide richer functionalities and better zone handling, addressing many of these challenges. Yet, in the context of Google Apps Script, where external libraries have limitations, understanding and leveraging the built-in methods effectively becomes crucial. Programmers coming from other languages may find the nuances of date handling in Google Apps Script uniquely challenging but can achieve robust date parsing with a deep understanding of the available tools and careful consideration of their applications’ global nature.