从对象调用函数

Question

I retrieve date by calling

event[0].getDateCreated() // output in GMT

but I want it to Local

I do not want to convert to local as

Utilities.formatDate(event[0].getDateCreated(), tz, "E, dd MMMM YYYY hh:mm a")

instead - I want to convert by using a function attached to date object

as

event[0].getDateCreated().toLcl()

should accomplish the above task.

How do I define a toLcl()

I tried with

function toLcl()
{
    return Utilities.formatDate(this, tz, "E, dd MMMM YYYY hh:mm a")
}

Answer 1

Use JavaScript Date prototype Property

The prototype constructor allows you to add new properties and methods to the Date() object.

Date.prototype.myMethod = function() {
    this.localDate = Utilities.formatDate(this, tz, "E, dd MMMM YYYY hh:mm a");

};

Use it like this :

var d = new Date();
d.myMethod();
var localDate = d.localDate;

Hope this helps !

Answer 2

You can add a property in the prototype of the Date . Do not alter the prototype directly. Use Object#defineProperty instead:

Object.defineProperty(Date.prototype, 'locale', {
  get: () => Utilities.formatDate(this, tz, "E, dd MMMM YYYY hh:mm a");
});

const myDate = new Date();
const localeDate = myDate.locale