---
title: monthStart()
slug: monthstart
docTags: 
createdAt: 2021-09-14T17:49:42.000Z
---

Returns the first day of a given month.

### Syntax

`monthStart([date])`

- `date` - (optional) the date from which to derive the first day of that date's month
- **Return type: **[Date](docId\:xTAQdzvLBTAKjxRnpFwe9) 

### Sample usage

`monthStart('2020-05-12')` returns `2020-05-01`.

### Supported data types

| **Input type**                            | **Return type**                         | **Logic**                                                                                                    |
| ----------------------------------------- | --------------------------------------- | ------------------------------------------------------------------------------------------------------------ |
| ****[Date](docId\:xTAQdzvLBTAKjxRnpFwe9)  | [Date](docId\:xTAQdzvLBTAKjxRnpFwe9)    | The input date specifies the desired month. The month is then used to determine the first day in that month. |
| *Unsupported data types*                  | **[Null](docId\:N9trVqonnBknqL9DrNBP6)  | Unsupported data types return `Null`.                                                                        |