JavaScript WorkerLocation search Property

What You’ll Learn

The search property of a WorkerLocation object returns the search (query string) of the worker’s location. Learn self.location.search, the leading ?, how it differs from hash and href, and how to demo it with blob worker URLs—with five examples and try-it labs.

Introduction

A search (query string) is the part of a URL that starts with ?—for example ?t=67 in https://example.com/path?t=67. Inside a worker, self.location.search returns that query for the worker script URL.

MDN’s classic idea: on a worker related to a URL with ?t=67, location.search can look like "?t=67".

Understanding the search Property

A read-only instance property on WorkerLocation that returns the worker’s query string as a string.

• Value — a string (e.g. "?t=67" or "").
• vs hash — search is ?…; hash is #….
• Access — self.location.search or location.search inside the worker.
• Workers only — not available on the main document thread.
• Baseline Widely available on MDN (since July 2015).

📝 Syntax

Read the property inside a worker script:

const result = self.location.search;
// e.g. "?t=67"

Value

A string.

Typical pattern (MDN idea)

// Inside a Web Worker
const result = self.location.search;
self.postMessage(result);

Demo tip: append a query to a blob worker URL

const base = URL.createObjectURL(new Blob(
  ["self.postMessage(location.search);"],
  { type: "application/javascript" }
));
const worker = new Worker(base + "?t=67");

⚖️ search vs Related Ideas

Examples Gallery

Examples follow MDN WorkerLocation.search. Labs append ?… to blob worker URLs so you can see a real query string.

const result = self.location.search;
// e.g. "?t=67"
self.postMessage(result);

?t=67

self.postMessage({
  search: location.search,
  hash: location.hash
});

search: "?t=67"
hash: "#demo"

// Worker
self.postMessage(location.search);

// Main: one Worker(base), one Worker(base + "?mode=demo")

without: ""
with: "?mode=demo"

// Worker
self.postMessage(location.search);

// Main
worker.onmessage = (e) => {
  const params = new URLSearchParams(e.data);
  console.log(params.get("t")); // "67"
};

search: "?t=67"
t: 67

// Worker
self.postMessage(location.search);

// Main
worker.onmessage = (e) => {
  console.log("worker:", e.data);
  console.log("page:", location.search);
};

worker: "?t=67"
page: ""

🚀 Common Use Cases

• Pass config flags to a worker via the script URL query.
• Log the worker query string for debugging.
• Parse keys with URLSearchParams.
• Distinguish query (search) from fragment (hash).
• Teach URL query concepts using workers.

🔧 How It Works

📝 Notes

• MDN: Baseline Widely available (since July 2015) — no Deprecated / Experimental / Non-standard banner.
• Only available in Web Workers (WorkerLocation / self.location).
• Read-only string; usually starts with ? when present.
• You can append ?… to blob worker URLs for demos (same idea as hash labs).
• Related learning: protocol, hash, href, Worker().

💡 Best Practices