---
title: strings.trimPrefix() function
description: strings.trimPrefix() removes a prefix from a string. Strings that do not start with the prefix are returned unchanged.
url: https://docs.influxdata.com/flux/v0/stdlib/strings/trimprefix/
estimated_tokens: 1404
product: Flux
version: v0
---

# strings.trimPrefix() function

-   Flux 0.18.0+
-   View InfluxDB support

`strings.trimPrefix()` removes a prefix from a string. Strings that do not start with the prefix are returned unchanged.

##### Function type signature

```js
(prefix: string, v: string) => string
```

For more information, see [Function type signatures](/flux/v0/function-type-signatures/).

## Parameters

### v

(Required) String to trim.

### prefix

(Required) Prefix to remove.

## Examples

### Trim a prefix from all values in a column

```js
import "sampledata"
import "strings"

sampledata.string()
    |> map(fn: (r) => ({r with _value: strings.trimPrefix(v: r._value, prefix: "smpl_")}))
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t1 | smpl_g9qczs |
| 2021-01-01T00:00:10Z | t1 | smpl_0mgv9n |
| 2021-01-01T00:00:20Z | t1 | smpl_phw664 |
| 2021-01-01T00:00:30Z | t1 | smpl_guvzy4 |
| 2021-01-01T00:00:40Z | t1 | smpl_5v3cce |
| 2021-01-01T00:00:50Z | t1 | smpl_s9fmgy |

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t2 | smpl_b5eida |
| 2021-01-01T00:00:10Z | t2 | smpl_eu4oxp |
| 2021-01-01T00:00:20Z | t2 | smpl_5g7tz4 |
| 2021-01-01T00:00:30Z | t2 | smpl_sox1ut |
| 2021-01-01T00:00:40Z | t2 | smpl_wfm757 |
| 2021-01-01T00:00:50Z | t2 | smpl_dtn2bv |

#### Output data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | g9qczs | t1 |
| 2021-01-01T00:00:10Z | 0mgv9n | t1 |
| 2021-01-01T00:00:20Z | phw664 | t1 |
| 2021-01-01T00:00:30Z | guvzy4 | t1 |
| 2021-01-01T00:00:40Z | 5v3cce | t1 |
| 2021-01-01T00:00:50Z | s9fmgy | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | b5eida | t2 |
| 2021-01-01T00:00:10Z | eu4oxp | t2 |
| 2021-01-01T00:00:20Z | 5g7tz4 | t2 |
| 2021-01-01T00:00:30Z | sox1ut | t2 |
| 2021-01-01T00:00:40Z | wfm757 | t2 |
| 2021-01-01T00:00:50Z | dtn2bv | t2 |

#### Related

-   [strings.trim() function](/flux/v0/stdlib/strings/trim/)
-   [strings.trimLeft() function](/flux/v0/stdlib/strings/trimleft/)
-   [strings.trimRight() function](/flux/v0/stdlib/strings/trimright/)
-   [strings.trimSuffix() function](/flux/v0/stdlib/strings/trimsuffix/)
-   [strings.trimSpace() function](/flux/v0/stdlib/strings/trimspace/)