JavaScript Navigator pdfViewerEnabled Property

What You’ll Learn

navigator.pdfViewerEnabled is a read-only Boolean that tells you whether the browser can show PDF files inline. Learn the MDN check pattern, how it replaces legacy MIME sniffing, UI messaging when PDFs download instead, five examples, and try-it labs.

Introduction

Many apps link to invoices, manuals, or reports as PDF files. Users expect either an in-browser preview or a download. Guessing that behavior from old plugin / MIME lists was fragile.

navigator.pdfViewerEnabled answers one clear question: can this browser display PDFs inline when navigating to them? If not, the PDF is downloaded and may open in an external application.

Understanding the pdfViewerEnabled Property

Think of it as a green / red light for inline PDF viewing. You read it once (or when choosing UI copy) — you never assign to it.

• true — browser can show PDFs inline (built-in viewer or PDF extension).
• false — navigating to a PDF downloads it (external app may handle it).
• Read-only — part of the HTML Navigator interface.
• Baseline — Widely available across modern browsers (MDN, since March 2023).

📝 Syntax

General form of the property:

navigator.pdfViewerEnabled

Value

• A Boolean indicating whether inline PDF viewing is supported.

Common patterns

// MDN pattern:
if (!navigator.pdfViewerEnabled) {
  // The browser does not support inline viewing of PDF files.
}

// Positive branch:
if (navigator.pdfViewerEnabled) {
  console.log("Inline PDF viewing looks available");
}

Examples Gallery

Examples follow MDN navigator.pdfViewerEnabled patterns. Prefer Try It Yourself to inspect your browser. Use View Output for expected messaging.

console.log(navigator.pdfViewerEnabled);

true
(or false if inline PDF viewing is unavailable)

if (!navigator.pdfViewerEnabled) {
  console.log("Inline PDF viewing not supported");
} else {
  console.log("Inline PDF viewing looks available");
}

Inline PDF viewing looks available

const msg = navigator.pdfViewerEnabled
  ? "PDF will open in the browser when possible."
  : "PDF will download — open it with a PDF app.";
console.log(msg);

PDF will open in the browser when possible.

const pdfEnabled = Boolean(navigator.pdfViewerEnabled);
const mimePdf =
  navigator.mimeTypes && "application/pdf" in navigator.mimeTypes;

console.log("pdfViewerEnabled: " + pdfEnabled);
console.log("mimeTypes has application/pdf: " + Boolean(mimePdf));
console.log("Prefer pdfViewerEnabled for new PDF UI decisions");

pdfViewerEnabled: true
mimeTypes has application/pdf: true
Prefer pdfViewerEnabled for new PDF UI decisions

function pdfViewStatus() {
  const inline = Boolean(navigator.pdfViewerEnabled);
  return {
    inline,
    suggestedTarget: inline ? "_blank" : "_self",
    tip: inline
      ? "Open PDF in a new tab for an inline preview."
      : "Expect a download; offer a clear Download PDF label."
  };
}

console.log(JSON.stringify(pdfViewStatus(), null, 2));

{
  "inline": true,
  "suggestedTarget": "_blank",
  "tip": "Open PDF in a new tab for an inline preview."
}

🚀 Common Use Cases

• Invoice / report links — label buttons as “View PDF” vs “Download PDF.”
• Docs hubs — prefer embed / new-tab preview when inline viewing is available.
• Help text — warn when the browser will download instead of preview.
• Migration — replace mimeTypes-based PDF sniffing with this Boolean.
• Diagnostics — include pdfViewerEnabled in support debug panels.

📝 Notes

• Baseline Widely available (MDN, since March 2023).
• Not Deprecated, Experimental, or Non-standard — no status banner required.
• Read-only Boolean on Navigator.
• Replaces several legacy methods of inferring inline PDF support.
• Headers and user settings can still affect a specific PDF response.
• Related: mimeTypes, oscpu, Window, JavaScript hub.

💡 Best Practices