How to Use FindTextAsync in ASP.NET Core PDF Viewer

14 Aug 20263 minutes to read

Use the findTextAsync method to search for text strings and retrieve bounding box coordinates for all matches. Perform case-sensitive or case-insensitive searches across the entire document or on specific pages.

Asynchronous text search with findTextAsync

@page "{handler?}"
@model IndexModel
@{
    ViewData["Title"] = "Home page";
}

<div class="text-center">
    <button onclick="findText()">Find Text</button>
    <button onclick="findTexts()">Find Multiple Texts</button>
    <ejs-pdfviewer id="pdfviewer" style="height:600px" resourceUrl="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2-pdfviewer-lib" documentPath="https://cdn.syncfusion.com/content/pdf/pdf-succinctly.pdf">
    </ejs-pdfviewer>
</div>

<script type="text/javascript">
    function findText() {
        var viewer = document.getElementById('pdfviewer').ej2_instances[0];
        // Search for a single text ('pdf') across all pages (case insensitive)
        viewer.textSearchModule.findTextAsync('pdf', false).then(function (res) {
            console.log(res);  // Log the search results for 'pdf'
        });
    }

    function findTexts() {
        var viewer = document.getElementById('pdfviewer').ej2_instances[0];
        // Search for multiple texts (['pdf', 'the']) across all pages (case insensitive)
        viewer.textSearchModule.findTextAsync(['pdf', 'the'], false).then(function (res) {
            console.log(res);  // Log the search results for 'pdf' and 'the'
        });
    }
</script>

Description

The findTextAsync method performs an asynchronous text search within a PDF document. You can search for a single string or multiple strings while controlling case sensitivity. By default, the search runs on all pages. Specify the optional pageIndex argument to limit the search to a single page.

Parameters

  • **text (string string[]):** String or array of strings to search for.

  • matchCase (boolean): Whether the search is case-sensitive. true matches exact case; false ignores case.

  • pageIndex (optional, number): Zero-based page index to search. If omitted, searches all pages. When text is an array, each string is searched only on the page specified by pageIndex. When pageIndex is provided, the search is restricted to that single page and the matchCase argument is still honored.

Example workflow

  • findTextAsync(‘pdf’, false): Searches for “pdf” case-insensitively across all pages.

  • findTextAsync([‘pdf’, ‘the’], false): Searches for “pdf” and “the” case-insensitively across all pages.

  • findTextAsync(‘pdf’, false, 0): Searches for “pdf” case-insensitively on page 0 only.

  • findTextAsync([‘pdf’, ‘the’], false, 1): Searches for “pdf” and “the” case-insensitively on page 1 only.

View sample on GitHub