---
title: strings.trimPrefix() function
description: >
  `strings.trimPrefix()` removes a prefix from a string. Strings that do not start with the prefix are returned unchanged.
menu:
  flux_v0_ref:
    name: strings.trimPrefix
    parent: strings
    identifier: strings/trimPrefix
weight: 101
---

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`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
```

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

## Parameters

### v
({{< req >}})
String to trim.



### prefix
({{< req >}})
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_")}))

```

{{< expand-wrapper >}}
{{% expand "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   |

{{% /expand %}}
{{< /expand-wrapper >}}