How to return the current timestamp with Moment.js?

Folks,

I am trying to understand the MomentJS API. What is the appropriate way to get the current time on the machine?

var CurrentDate = moment();

vs

var CurrentDate = moment().format();

Trying to parse their docs, and its not apparent what to use.

http://momentjs.com/docs/#/query/is-a-moment/

Here you are assigning an instance of momentjs to CurrentDate:

var CurrentDate = moment();

Here just a string, the result from default formatting of a momentjs instance:

var CurrentDate = moment().format();

And here the number of seconds since january of... well, unix timestamp:

var CurrentDate = moment().unix();

And here another string as ISO 8601 (What's the difference between ISO 8601 and RFC 3339 Date Formats?):

var CurrentDate = moment().toISOString();

And this can be done too:

var a = moment();
var b = moment(a.toISOString());

console.log(a.isSame(b)); // true

moment().unix() you will get a unix timestamp (in seconds)

moment().valueOf() you will get a full timestamp (in milliseconds)