trim_start()

Applies to: ✅ Microsoft Fabric ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel

Removes leading match of the specified regular expression.

Syntax

trim_start(regex, source)

Learn more about syntax conventions.

Parameters

Name	Type	Required	Description
regex	string	✔️	The string or regular expression to be trimmed from the beginning of source.
source	string	✔️	The source string from which to trim regex.

Returns

source after trimming match of regex found in the beginning of source.

Examples

Trim specific substring

The following example trims substring from the start of string_to_trim.

Run the query

let string_to_trim = @"https://bing.com";
let substring = "https://";
print string_to_trim = string_to_trim,trimmed_string = trim_start(substring,string_to_trim)

Output

string_to_trim	trimmed_string
https://bing.com	bing.com

Trim non-alphanumeric characters

The following example trims all non-word characters from the beginning of the string.

Run the query

range x from 1 to 5 step 1
| project str = strcat("-  ","Te st",x,@"// $")
| extend trimmed_str = trim_start(@"[^\w]+",str)

Output

str	trimmed_str
- Te st1// $	Te st1// $
- Te st2// $	Te st2// $
- Te st3// $	Te st3// $
- Te st4// $	Te st4// $
- Te st5// $	Te st5// $

Trim whitespace

The following example trims all spaces from the start of the string.

Run the query

let string_to_trim = @"    Hello, world!    ";
let substring = @"\s+";
print
    string_to_trim = string_to_trim,
    trimmed_start = trim_start(substring, string_to_trim)

Output

string_to_trim	trimmed_start
Hello, world!	Hello, world!