Search Text in HTML Documents Leave feedback

id: search-text-in-html-documents url: parser/net/search-text-in-html-documents title: Search text in HTML documents weight: 2 description: “To search a keyword in HTML documents Search(String) method is used. This method returns the collection of SearchResult objects.” keywords: search a keyword, search a keyword in HTML productName: GroupDocs.Parser for .NET hideChildren: False toc: true

To search a keyword in HTML documents Search(String) method is used. This method returns the collection of SearchResult objects. For details, see Search Text.

Warning

Parsing does not execute JavaScript or fetch external content; for dynamically generated HTML, pre-render or extract the actual text content before searching.

Here are the steps to search a keyword in HTML document:

• Instantiate Parser object for the initial document;
• Call Search(string) method and obtain the collection of SearchResult objects;
• Iterate through the collection and get the position and text.

Warning

Search(String) method returns null value if search isn’t supported for the document. For example, text extraction isn’t supported for Zip archive. Therefore, for Zip archive Search(String) method returns null. For empty HTML document Search(String) method returns an empty collection.

The following example shows how to find a keyword in HTML document:

// Create an instance of Parser class
using(Parser parser = new Parser(filePath))
{
    // Search a keyword:
    IEnumerable<SearchResult> sr = parser.Search("page number");
   
    // Iterate over search results
    foreach(SearchResult s in sr)
    {
        // Print an index and found text:
        Console.WriteLine(string.Format("At {0}: {1}", s.Position, s.Text));
    }
}

Search(String, SearchOptions) is used for the advanced search in HTML documents - like search with regular expressions. SearchOptions parameter is used to customize a search.

Here are the steps to search with a regular expression in HTML document:

• Instantiate Parser object for the initial document;
• Instantiate SearchOptions object with the parameters for the search;
• Call Search(string, SearchOptions) method and obtain the collection of SearchResult objects;
• Iterate through the collection and get the position and text.

The following example shows how to search with a regular expression in HTML document:

// Create an instance of Parser class
using(Parser parser = new Parser(filePath))
{
    // Search with a regular expression with case matching
    IEnumerable<SearchResult> sr = parser.Search("page number: [0-9]+", new SearchOptions(true, false, true));
    // Iterate over search results
    foreach(SearchResult s in sr)
    {
        // Print an index and found text:
        Console.WriteLine(string.Format("At {0}: {1}", s.Position, s.Text));
    }
}

The Search() method behaves differently depending on the document type and its text content:

• Returns null → when the document type does not support searching (e.g., ZIP archives, images, or other non-text formats).
• Returns an empty collection → when the document supports searching (like HTML) but contains no searchable text.

using (Parser parser = new Parser("sample.zip")) // ZIP archives are not searchable
{
    var results = parser.Search("example");    
    
    if (results == null)
        Console.WriteLine("Search returned null: document type does not support searching.");
}

using (Parser parser = new Parser("empty.html")) // Empty HTML without text
{
    var results = parser.Search("example");
    if (results != null && results.Count == 0)
        Console.WriteLine("Search returned empty collection: no text found in the document.");
}

using (Parser parser = new Parser("sample.html")) // Contains text
{
    var results = parser.Search("example");
    if (results != null)
    {
        foreach (var result in results)
            Console.WriteLine($"Found: '{result.Text}' at position {result.Position}");
    }
}

GroupDocs.Parser works with the raw text content of HTML documents.
It does not execute JavaScript or load external resources (such as CSS, images, or scripts).
If your HTML file relies on JavaScript to generate content dynamically, the parser may return an empty collection.

To improve results, consider the following preprocessing steps:

Ensure that the HTML file you provide already contains the visible text content.
If your HTML is generated by a web application, save or export the fully rendered version of the page before passing it to the parser.

If possible, simplify your HTML by removing scripts, styles, or metadata that do not affect the visible text.
This reduces noise and makes search results more accurate.

Verify that the HTML file uses a standard encoding (such as UTF-8).
Unexpected or inconsistent encodings may cause missing or unreadable text when searching.

If search results are empty, open the HTML file in a text editor to confirm whether actual text is present in the markup.
If the content only appears after running JavaScript in a browser, it will not be searchable.

Summary:
Provide static, text-based HTML whenever possible.
Dynamic or script-driven HTML will not yield results unless converted into plain text or pre-rendered before parsing.

You may easily run the code above and see the feature in action in our GitHub examples:

• GroupDocs.Parser for .NET examples
• GroupDocs.Parser for Java examples

Along with full featured .NET library we provide simple, but powerful free Apps.

You are welcome to parse documents and extract data from PDF, DOC, DOCX, PPT, PPTX, XLS, XLSX, Emails and more with our free online Free Online Document Parser App.