Simplify nextTick and setImmediate definitions

Author: megawac

lib/async.js

@@ -188,38 +188,22 @@
     //// nextTick implementation with browser-compatible fallback ////
 
     // capture the global reference to guard against fakeTimer mocks
-    var _setImmediate;
-    if (typeof setImmediate === 'function') {
-        _setImmediate = setImmediate;
-    }
+    var _setImmediate = typeof setImmediate === 'function' && setImmediate;
 
-    if (typeof process === 'undefined' || !(process.nextTick)) {
-        if (_setImmediate) {
-            async.nextTick = function (fn) {
-                // not a direct alias for IE10 compatibility
-                _setImmediate(fn);
-            };
-            async.setImmediate = async.nextTick;
-        }
-        else {
-            async.nextTick = function (fn) {
-                setTimeout(fn, 0);
-            };
-            async.setImmediate = async.nextTick;
-        }
-    }
-    else {
+    var _delay = _setImmediate ? function(fn) {
+        // not a direct alias for IE10 compatibility
+        _setImmediate(fn);
+    } : function(fn) {
+        setTimeout(fn, 0);
+    };
+
+    if (typeof process === 'object' && typeof process.nextTick === 'function') {
         async.nextTick = process.nextTick;
-        if (_setImmediate) {
-            async.setImmediate = function (fn) {
-              // not a direct alias for IE10 compatibility
-                _setImmediate(fn);
-            };
-        }
-        else {
-            async.setImmediate = async.nextTick;
-        }
+    } else {
+        async.nextTick = _delay;
     }
+    async.setImmediate = _setImmediate ? _delay : async.nextTick;
+
 
     async.forEach =
     async.each = function (arr, iterator, callback) {