Convert a string to date in google apps script

Question

I am new to GAS (actually new to coding too) I got a date string in the format of yyyymmdd (eg. 20140807), how could I turn it to date so that Google apps script can recognize it and later I can do some calculation (mostly to compare with Today as in var today = new Date();)

Google apps script can't recognize the following correctly:

// string is in the format of yyyymmdd (eg. 20140807)
var pubdate = new Date(string)

Answer 1

The only way - parse the string by hand:

var dateStr = "20140807"

var year = +dateStr.substring(0, 4)
var month = +dateStr.substring(4, 6)
var day = +dateStr.substring(6, 8)

var pubdate = new Date(year, month - 1, day)

The reason for month - 1 is that the month numeration starts from 0.

And the + sign before function just converts string, which is returned by functions, to numbers so we can pass them right into new Date()

Answer 2

You can use moment.js to parse a string of date in GAS.

First you need to add moment.js to your GAS. In script editor, go to "Resources" then "Libraries...", then put this project key MHMchiX6c1bwSqGM1PZiW_PxhMjh3Sh48 and click "Add". Choose the version from the dropdown, then click "Save".

Parsing date with moment is as easy as this.

var momentDate = Moment.moment("20140807", "YYYY/MM/DD");

What's returned here is a moment object, which is a wrapper of JavaScript's native Date object and very handy for date manipulation .

But, if you still need to get JavaScript's Date object, you can get it like this;

var date = momentDate.toDate();

You can also create formatted date time string with moment.js. Here is the reference for the tokens to specify format.