Why Do I Have to Manually Copy Files from node_modules into My App?

17 Oct 20251 minute to read

The PDF Viewer supports multiple build systems and can work without a bundler by referencing assets directly using HTML tags. To keep load times efficient, the library is split into smaller modules and uses lazy loading for certain assets.

• The primary entry point, “pdfium.js”, is typically included by bundlers automatically.
• Additional resources under “ej2-pdfviewer-lib” are loaded on demand at runtime. Because the host app does not know about these lazy-loaded files, they are not automatically emitted by bundlers or available to static servers unless they are copied and referenced.

When not using a bundler (or when the bundler does not emit these assets), copy the required files from node_modules to a web-accessible path in your app (for example, “src/ej2-pdfviewer-lib”) and reference them accordingly. This ensures the viewer can fetch the lazy-loaded assets when needed and prevents runtime 404 errors.

If a bundler is configured to emit static assets from node_modules, verify that the output contains the necessary files from “@syncfusion/ej2-pdfviewer/dist/ej2-pdfviewer-lib” and that your app serves them from a public path. Otherwise, perform a manual copy step during your build process.