Oftentimes, especially in API calls, dates and times need to be entered into the call in a specific way. JavaScript offers the handy Date(); object, which makes it easy to call the current time or create and store a date in the past or future, but formatting the result into a custom format (such as mm/dd/yy or yyy/mm/dd/hh/mm/ss) is not possible, as best I could tell, in vanilla JavaScript.
Luckily, the app I was building ran on AngularJS, and so I could leverage Angular’s handy built in filters, specifically, the date filter. Because the API call was being handled in a service, though, I didn’t implement the date filter in the way you do in the view in Angular, which is the more common way (to write, say {{myDate | date: 'yy/mm/dd'}} in the HTML view itself.)
First, I set a variable with the plain old unformatted JavaScript date. If you want the present time, just use:
var myTimeUnformatted = new Date();
But if you need, say, last week’s date, then do:
var lastWeekUnformatted = new Date(
new Date().setDate(new Date().getDate() - 7)
);
This will return a date in this format: Wed Apr 30 2014 16:33:22 GMT-0700 (PDT)
Now, to convert this date into whatever format we need (inside an Angular app!), enter $filter. First, because we are not working in the view, but in a service or controller or other part of the app, you have to inject $filter into wherever you are calling it, much like you inject other Angular services like $http or $scope. In this case, I was calling $filter in a custom service, so you just enter it where you do other injections, for example:
angular.module('myApp')
.factory('myService', function ($filter, $http) { ...etc, etc
Now, it’s as simple as following the way the date filter$ is documented in the API:
var lastWeek = $filter("date")(lastWeekUnformatted, "yyyy-MM-dd");
Of course, here is where you can customize the output as you please, using the API doc linked to above. The example above would output: 2014-04-30
And it’s as easy as that to get a date into an exact format required by an API or anything else in your application.