n8n-docs/docs/reference/javascript-code-snippets.md

# JavaScript Code Snippets

In n8n, you can write custom JavaScript code snippets to add, remove, and update the data you receive from a node. You can also use code snippets to modify the data structure of the data returned by a node.

::: tip 💡 Keep in mind
We are using Set node for illustrating expressions here. However, you can use the code snippets as an expression in any node. To do that, click on the gears icon next to a field and click on ***Add Expression***.
:::

For each section, we'll share code snippets that can be used in the function node as well as the expressions. You can read more about [Expressions](../nodes/expressions.md) and adding code snippets to the [Function](../nodes/nodes-library/core-nodes/Function/README.md) node in our documentation.


## Date and Time

The JavaScript [Date](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) object is a built-in object that stores the date and time. It provides several methods for managing and formatting the date. 

It's important to keep in mind that while the time value at the heart of a Date object is UTC, the basic methods to fetch the date and time or its components all work in the local time zone and offset. For example, `new Date().toISOString()` would show the time in UTC but `new Date().getHours()` would show the time in your local time zone.

**Note:** The outputs below either show the date and time when this documentation was created or are relative to it. The date and time will be different for you.


### 1. Get current timestamp

To use the built-in methods for managing and formatting date in JavaScript, you have to create a date object. The `Date()` constructor returns the date and time in the [ISO](https://en.wikipedia.org/wiki/ISO_8601) format. The `toISOString()` method converts the object to a string. To get the current timestamp use the following snippet.

#### Function node

```js
const today = new Date().toISOString();

items[0].json.today = today;
return items;
```

The output will be similar to the following.

```js
[
  {
    "today": "2020-10-13T09:35:42.588Z" 
  }
]
```

#### Expression editor

```js
{{new Date()}}
```

The expression would resolve to something similar to the following.

```js
2020-10-13T09:39:12.939Z
```

### 2. Get date

Use the `getDate()` method to get today's date.

#### Function node
```js
const today = new Date();
const date = today.getDate();

items[0].json.today_date = date;
return items;
```

The output will be similar to the following.

```js
[
  {
    "today_date": 13
  }
]
```

#### Expression editor

```js
{{new Date().getDate()}}
```

The expression would resolve to something similar to the following.

```js
13
```

### 3. Get month

In JavaScript, the month is 0-indexed. For example, January has index 0, February has index 1, and so on. Use the `getMonth()` method to get the month.

#### Function node
```js
const today = new Date();
const month = today.getMonth()+1;

items[0].json.month = month;
return items;
```

The output will be similar to the following.

```js
[
  {
    "month": 10 
  }
]
```

#### Expression editor

```js
{{new Date().getMonth()+1}}
```

The expression would resolve to something similar to the following.

```js
10
```


### 4. First and last days of the last month

Use the following snippet to get the first and last days of the last month.

#### Function node
```js
const today = new Date();

const current_month = today.getMonth();
const year = today.getFullYear()

const first_day_last_month = new Date(year, current_month-1, 1).toISOString();
const last_day_last_month = new Date(year, current_month, 1).toISOString();

items[0].json.first_day_last_month = first_day_last_month;
items[0].json.last_day_last_month = last_day_last_month;
return items;
```
The output will be similar to the following.

```js
[
  {
    "first_day_last_month": "2020-08-31T22:00:00.000Z",
    "last_day_last_month": "2020-09-30T22:00:00.000Z" 
  }
]
```

#### Expression editor

First day of the last month

```js
{{new Date(new Date().getFullYear(), new Date().getMonth()-1, 1).toISOString()}}
```

Last day of the last month

```js
{{new Date(new Date().getFullYear(), new Date().getMonth(), 1).toISOString()}}
```

The expression would resolve to something similar to the following.

```js
// First day of the last month
2020-08-31T22:00:00.000Z

// Last day of the last month
2020-09-30T22:00:00.000Z
```