feat: add support for custom HTTP headers via cfg.customHeaders

README.md

@@ -341,6 +341,23 @@ Supported values: `get`, `post`, `put`, `patch`, `delete`, `sse`.
 
 These headers allow the server to detect µJS requests and adapt its response (e.g. return a fragment instead of a full page, skip analytics, return lighter content on prefetch).
 
+### Custom headers
+
+You can send additional HTTP headers with every request by setting the `headers` option in the configuration:
+
+```javascript
+mu.init({
+    headers: {
+        "Authorization": "Bearer " + myToken,
+        "Accept-Language": "fr-FR"
+    }
+});
+```
+
+These headers are merged into both regular and prefetch requests. µJS's internal headers (`X-Requested-With`, `X-Mu-Mode`, `X-Mu-Method`, `X-Mu-Prefetch`) always take precedence and cannot be overridden through this option.
+
+For per-request or dynamic headers (e.g. a fresh CSRF token on each request), listen to the `mu:before-fetch` event and modify `event.detail.config` instead.
+
 
 ## Triggers
 

lib/mu.js

@@ -984,8 +984,14 @@ var mu = mu || new function() {
 				return;
 			// Store the fetch promise so _loadExec can await it (even if still in-flight)
 			var fetchUrl = mu._cfg.urlPrefix ? mu._cfg.urlPrefix + url : url;
+			var prefetchHeaders = {};
+			// Merge custom headers if provided
+			if (mu._cfg.headers)
+				Object.assign(prefetchHeaders, mu._cfg.headers);
+			prefetchHeaders["X-Requested-With"] = "XMLHttpRequest";
+			prefetchHeaders["X-Mu-Prefetch"] = "1";	
 			var promise = fetch(fetchUrl, {
-				headers: {"X-Requested-With": "XMLHttpRequest", "X-Mu-Prefetch": "1"},
+				headers: prefetchHeaders,
 				priority: "low"
 			})
 			.then(function(r) { return (r.ok ? r.text() : null); })
@@ -1313,16 +1319,18 @@ var mu = mu || new function() {
 				// Build fetch options
 				var fetchOpts = {
 					signal: abortCtrl.signal,
-					headers: {
-						"X-Requested-With": "XMLHttpRequest",
-						"X-Mu-Mode": cfg.mode
-					}
+					headers: {}
 				};
 				if (method !== "get") {
 					fetchOpts.headers["X-Mu-Method"] = fetchOpts.method = method.toUpperCase();
 					if (cfg.postData)
 						fetchOpts.body = cfg.postData;
 				}
+				// Merge custom headers if provided
+				if (cfg.headers)
+					Object.assign(fetchOpts.headers, cfg.headers);
+				fetchOpts.headers["X-Requested-With"] = "XMLHttpRequest";
+				fetchOpts.headers["X-Mu-Mode"] = cfg.mode;
 				resp = await fetch(fetchUrl, fetchOpts);
 				if (!resp.ok) {
 					mu._emit("mu:fetch-error", {url: url, fetchUrl: fetchUrl, status: resp.status, response: resp});