index.md

---

title: substring-before
slug: Web/XPath/Functions/substring-before

---

{{ XsltRef() }}

The substring-before function returns a string that is the part of a given string before a given substring.

Syntax

substring-before( haystack, needle )

Arguments

• haystack

  • : The string to be evaluated. Part of this string will be returned.

• needle

  • : The substring to search for. Everything before the first occurrence of needle in haystack will be returned.

Returns

A string.

Examples

XPath Example	Output
substring-before('aa-bb','-')	aa
substring-before('aa-bb','a')	(empty string)
substring-before('aa-bb','b')	aa-
substring-before('aa-bb','q')	(empty string)

Defined

XPath 1.0 4.2

Gecko support

Supported.