How can I convert a date into an integer?

I have an array of dates and have been using the map function to iterate through it, but I can't figure out the JavaScript code for converting them into integers.

This is the array of dates:

var dates_as_int = [
    "2016-07-19T20:23:01.804Z",
    "2016-07-20T15:43:54.776Z",
    "2016-07-22T14:53:38.634Z",
    "2016-07-25T14:39:34.527Z"
];

var dates = dates_as_int.map(function(dateStr) {
    return new Date(dateStr).getTime();
});

=>

[1468959781804, 1469029434776, 1469199218634, 1469457574527]

---

Update: ES6 version:

const dates = dates_as_int.map(date => new Date(date).getTime())

Using the builtin Date.parse function which accepts input in ISO8601 format and directly returns the desired integer return value:

var dates_as_int = dates.map(Date.parse);

Here what you can try:

var d = Date.parse("2016-07-19T20:23:01.804Z");
alert(d); //this is in milliseconds

You can run it through Number()

var myInt = Number(new Date(dates_as_int[0]));

> If the parameter is a Date object, the Number() function returns the number of milliseconds since midnight January 1, 1970 UTC.

Use of Number()