Add out-of-the-box support for browser using Fetch API

README.md

@@ -23,8 +23,6 @@ tmx.parseFile(filename, function(err, map) {
 
 The second example in that list uses `tmx.readFile(filename, callback)`
 and then calls `tmx.parse(...)` on the results.
-So if you're in browserland, you can replace the `readFile` function
-with your own asset loading function.
 
 ## Documentation
 
@@ -146,4 +144,4 @@ The `objects` array looks like this:
 TileLayer objects have a `tileAt(x, y)` method.
 Otherwise you can access `layer.tiles` in row-major order.
 
-See the bottom of index.js for more information.
+See the bottom of index.js for more information.

index.js

@@ -686,7 +686,18 @@ function parse(content, pathToFile, cb) {
 }
 
 function defaultReadFile(name, cb) {
-  fs.readFile(name, { encoding: 'utf8' }, cb);
+  var isBrowser = typeof window !== 'undefined';
+
+  if (isBrowser) {
+    fetch(name)
+      .then(response => response.text())
+      .then(data => {
+        cb(undefined, data);
+      })
+      .catch(e => cb(e));
+  } else {
+    fs.readFile(name, { encoding: 'utf8' }, cb);
+  }
 }
 
 function parseFile(name, cb) {