Merge pull request jashkenas#1629 from dontfidget/re-entrant

fix throttle and debounce to be re-entrant
mponizil · May 7, 2014 · 29a973f · 29a973f
2 parents 530fc78 + fd69f5b
commit 29a973f
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Showing 2 changed files with 54 additions and 3 deletions.
diff --git a/test/functions.js b/test/functions.js
@@ -311,6 +311,29 @@
     }, 200);
   });
 
+  asyncTest('throttle re-entrant', 2, function() {
+    var sequence = [
+      ['b1', 'b2'],
+      ['c1', 'c2']
+    ];
+    var value = '';
+    var throttledAppend;
+    var append = function(arg){
+      value += this + arg;
+      var args = sequence.pop()
+      if (args) {
+        throttledAppend.call(args[0], args[1]);
+      }
+    };
+    throttledAppend = _.throttle(append, 32);
+    throttledAppend.call('a1', 'a2');
+    equal(value, 'a1a2');
+    _.delay(function(){
+      equal(value, 'a1a2c1c2b1b2', 'append was throttled successfully');
+      start();
+    }, 100);
+  });
+
   asyncTest('debounce', 1, function() {
     var counter = 0;
     var incr = function(){ counter++; };
@@ -369,6 +392,28 @@
     }, 200);
   });
 
+  asyncTest('debounce re-entrant', 2, function() {
+    var sequence = [
+      ['b1', 'b2']
+    ];
+    var value = '';
+    var debouncedAppend;
+    var append = function(arg){
+      value += this + arg;
+      var args = sequence.pop()
+      if (args) {
+        debouncedAppend.call(args[0], args[1]);
+      }
+    };
+    debouncedAppend = _.debounce(append, 32);
+    debouncedAppend.call('a1', 'a2');
+    equal(value, '');
+    _.delay(function(){
+      equal(value, 'a1a2b1b2', 'append was debounced successfully');
+      start();
+    }, 100);
+  });
+
   test('once', function() {
     var num = 0;
     var increment = _.once(function(){ num++; });

diff --git a/underscore.js b/underscore.js
@@ -679,7 +679,9 @@
       previous = options.leading === false ? 0 : _.now();
       timeout = null;
       result = func.apply(context, args);
-      context = args = null;
+      if (!timeout) {
+        context = args = null;
+      }
     };
     return function() {
       var now = _.now();
@@ -692,7 +694,9 @@
         timeout = null;
         previous = now;
         result = func.apply(context, args);
-        context = args = null;
+        if (!timeout) {
+          context = args = null;
+        }
       } else if (!timeout && options.trailing !== false) {
         timeout = setTimeout(later, remaining);
       }
@@ -716,7 +720,9 @@
         timeout = null;
         if (!immediate) {
           result = func.apply(context, args);
-          context = args = null;
+          if (!timeout) {
+            context = args = null;
+          }
         }
       }
     };