How to Achieve Case-Insensitive contains() Functionality in XPath 1.0?

XPath's Case-Insensitive contains()

In XSLT or other DOM-traversing applications, performing XPath queries with case-sensitive string comparisons can be limiting. However, achieving case-insensitive contains() functionality in XPath 1.0 is possible.

1. Translation-Based Method (XPath 1.0)

To match both case-sensitive and case-insensitive variations of a string, employ the translate() function:

/html/body//text()[
  contains(
    translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'),
    'test'
  )
]

This method effectively translates all uppercase letters to lowercase, enabling case-insensitive comparisons. However, it requires knowledge of the expected character set.

2. JavaScript-Assisted Dynamic XPath Generation

If manipulating the XPath expression is possible, you can use JavaScript to dynamically replace the search string with its upper and lowercase variants:

<code class="javascript">function xpathPrepare(xpath, searchString) {
  return xpath.replace("$u", searchString.toUpperCase())
              .replace("$l", searchString.toLowerCase())
              .replace("$s", searchString.toLowerCase());
}

xp = xpathPrepare("//text()[contains(translate(., '$u', '$l'), '$s')]", "Test");</code>

This method handles search strings with arbitrary characters, including single quotes.

Caution: These techniques may not perform optimally if complex/large string operations are involved. If possible, consider other solutions such as storing strings with known character sets or adopting XPath 2.0, which natively supports case-insensitive string comparisons.

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