> For the complete documentation index, see [llms.txt](https://lochiwei.gitbook.io/web/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://lochiwei.gitbook.io/web/js/val/builtin/date.md).

# Date

[JS](/web/js.md) ⟩ [object](/web/js/val/obj.md) ⟩ [built-in](/web/js/val/builtin.md) ⟩ Date

{% hint style="success" %}
points in time.

```javascript
new Date()                                // current date and time
// month starts from 0, be careful❗️ 
new Date(2009, 11, 9)                     // December❗️ 
new Date(2009, 11, 9, 12, 59, 59, 999)
```

{% endhint %}

{% tabs %}
{% tab title="🧨 雷區" %}
{% hint style="danger" %}

* <mark style="color:yellow;">**month**</mark> numbers <mark style="color:yellow;">**start at**</mark> <mark style="color:red;">**0**</mark> (<mark style="color:red;">**11**</mark> = <mark style="color:yellow;">**December**</mark>),&#x20;
* <mark style="color:yellow;">**day**</mark> numbers <mark style="color:yellow;">**start at**</mark>**&#x20;**<mark style="color:red;">**1**</mark>.&#x20;

This is confusing and silly. Be careful:exclamation:
{% endhint %}
{% endtab %}

{% tab title="⭐️ 重點" %}
{% hint style="info" %} <mark style="color:purple;">**Date**</mark> is the <mark style="color:red;">**only**</mark>**&#x20;**<mark style="color:yellow;">**built-in type**</mark> that uses "[<mark style="color:yellow;">**prefer-**</mark><mark style="color:red;">**string**</mark>](/web/js/val/obj/convert/obj-to-prim.md)" [<mark style="color:yellow;">**object -> primitive conversion**</mark>](/web/js/val/obj/convert/obj-to-prim.md) algorithm.
{% endhint %}
{% endtab %}

{% tab title="💈範例" %}

```javascript
// Timestamps: 
// - milliseconds since the start of 1970 (UTC time zone).
new Date(2013, 11, 19).getTime()    // 1387407600000
Date.now                            // (current timestamp)
```

{% endtab %}

{% tab title="📗 參考" %}

* [ ] Eloquent JS ⟩ [The Date Class](https://eloquentjavascript.net/09_regexp.html#h_8U7L7LCU27)
  {% endtab %}

{% tab title="📘 手冊" %}

* [Date](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date)
  {% endtab %}
  {% endtabs %}