Create Rate Limiter.js

Author: chihungyu1116

Rate Limiter.js

@@ -0,0 +1,28 @@
+function* generator() {
+  var rate = 5;
+  var per = 8;
+  var lastTime = Date.now();      
+  var allowance = rate; // unit: messages
+
+  while(true) {
+    var currentTime = Date.now();
+    var timeElapsed = (currentTime - lastTime)/1000;
+    var lastTime = currentTime;
+    var addedTime = timeElapsed*(rate/per);
+    
+    allowance += addedTime;
+    
+    
+    console.log('allowance',allowance, addedTime);
+    if(allowance > rate) {
+      allowance = rate;
+    }
+    
+    if (allowance < 1.0) {
+      yield false;
+    } else {
+      allowance -= 1.0;
+      yield true;
+    }
+  }
+}