Initial draft of _.throttle and _.debounce

underscore.js

@@ -419,6 +419,33 @@
     return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
   };
 
+  // Internal function used to implement `_.throttle` and `_.debounce`.
+  var limit = function(func, wait, debounce) {
+    var timeout;
+    return function() {
+      var context = this, args = arguments;
+      var throttler = function() {
+        timeout = null;
+        func.apply(context, args);
+      };
+      if (debounce) clearTimeout(timeout);
+      if (debounce || !timeout) timeout = setTimeout(throttler, wait);
+    };
+  };
+
+  // Returns a function, that, when invoked, will only be triggered at most once
+  // during a given window of time.
+  _.throttle = function(func, wait) {
+    return limit(func, wait, false);
+  };
+
+  // Returns a function, that, as long as it continues to be invoked, will not
+  // be triggered. The function will be called after it stops being called for
+  // N milliseconds.
+  _.debounce = function(func, wait) {
+    return limit(func, wait, true);
+  };
+
   // Returns the first function passed as an argument to the second,
   // allowing you to adjust arguments, run code before and after, and
   // conditionally execute the original function.