---
title: startsWith
description: |
  Returns `true` if a string begins with a given substring, otherwise return `false`.

  !!! note
      Unlike `contains`, which checks for a substring anywhere in the string, `startsWith` only matches the beginning.
url: https://coralogix.com/docs/dataprime/language-reference/functions-reference/string/startswith/
product: dataengine
feature: DataPrime Language
feature_id: dataprime-language
feature_identifier: dataengine/dataprime-language
last_updated: '2026-10-21'
---

# `startsWith`

## Description

Returns `true` if a string begins with a given substring, otherwise return `false`.

Note

Unlike `contains`, which checks for a substring anywhere in the string, `startsWith` only matches the beginning.

## Syntax

Like many functions in DataPrime, `startsWith` supports<!-- --> [two notations](https://coralogix.com/docs/dataprime/language-reference/functions-reference.md),<!-- --> **function** and **method**. These interchangeable forms allow flexibility in how you structure expressions.

* Function notation
* Method notation

```
startsWith(value: string, prefix: string): bool
```

```
(value: string).startsWith(prefix: string): bool
```

## Arguments

| Name     | Type     | Required | Description                                                |
| -------- | -------- | -------- | ---------------------------------------------------------- |
| `value`  | `string` | **true** | The full string to test (haystack)                         |
| `prefix` | `string` | **true** | The substring to check at the start of the string (needle) |

## Example

**Check if a string is an AWS ARN**

AWS ARNs look like this:

```
arn:aws:s3:::mybucket
```

To confirm if a value is an ARN, check if it starts with `arn:`:

### Example query

* Function notation
* Method notation

```
create is_arn from startsWith(resource_id, 'arn:')
```

```
create is_arn from resource_id.startsWith('arn:')
```

### Example output

```
{

    "resource_id": "arn:aws:s3:::mybucket",

    "is_arn": true

}
```