find_first

Description

Given the subject string, find_first() returns the zero-based index of the first occurence where the sub substring appears in subject or null if it does not appear. If either the $subject or the $sub argument is an empty string, find_first() return null.

The start and end parameters are optional and allow restricting the range within subject in which sub must be found.

• If start is omitted, it defaults to 0 (which is the start of the subject string).
• If end is omitted, it defaults to length(subject) - 1 (which is is the end of the subject string).

If not omitted, the $start and $end arguments are expected to be integers. Othewise, an error MUST be raised.

Contrary to similar functions found in most popular programming languages, the find_first() function does not return -1 if no occurrence of the substring can be found. Instead, it returns null for consistency reasons with how JMESPath behaves.

Arguments

Required

Name	Type	Description
subject	string	Subject string
sub	string	Substring

Optional

Name	Type	Description
start	number	Position in the subject string where searching should start.
end	number	Position in the subject string where searching should end.

Returns

Type: number

Examples

search(find_first(@, string), "subject string") → 8

search(find_first(@, string, `0`), "subject string") → 8

search(find_first(@, string, `0`, `14`), "subject string") → 8

search(find_first(@, string, `-99`, `100`), "subject string") → 8

search(find_first(@, string, `0`, `13`), "subject string") → null

search(find_first(@, string, `8`), "subject string") → 8

search(find_first(@, string, `9`), "subject string") → null

search(find_first(@, s, `0`), "subject string") → 0

search(find_first(@, s, `1`), "subject string") → 8