Added the underscore node_module.

node_modules/underscore/cjs/debounce.js

@@ -0,0 +1,42 @@
+var restArguments = require('./restArguments.js');
+var now = require('./now.js');
+
+// When a sequence of calls of the returned function ends, the argument
+// function is triggered. The end of a sequence is defined by the `wait`
+// parameter. If `immediate` is passed, the argument function will be
+// triggered at the beginning of the sequence instead of at the end.
+function debounce(func, wait, immediate) {
+  var timeout, previous, args, result, context;
+
+  var later = function() {
+    var passed = now() - previous;
+    if (wait > passed) {
+      timeout = setTimeout(later, wait - passed);
+    } else {
+      timeout = null;
+      if (!immediate) result = func.apply(context, args);
+      // This check is needed because `func` can recursively invoke `debounced`.
+      if (!timeout) args = context = null;
+    }
+  };
+
+  var debounced = restArguments(function(_args) {
+    context = this;
+    args = _args;
+    previous = now();
+    if (!timeout) {
+      timeout = setTimeout(later, wait);
+      if (immediate) result = func.apply(context, args);
+    }
+    return result;
+  });
+
+  debounced.cancel = function() {
+    clearTimeout(timeout);
+    timeout = args = context = null;
+  };
+
+  return debounced;
+}
+
+module.exports = debounce;