Assignments completed

README.md

@@ -1,2 +1,4 @@
 # assignment_async_nodejs
 Async Node.js sprint
+
+Test

data/lorem.txt

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+Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

data/test.txt

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+Hello!Hello again!

event_emitter.js

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+function EventEmitter() {
+  this.listeners = [];
+}
+
+EventEmitter.prototype.on = function(eventType, callback) {
+  this.listeners.unshift([eventType, callback]);
+};
+
+EventEmitter.prototype.emit = function(eventType) {
+  // find all listeners with the eventType
+  var events = this.listeners.filter(function(listener) {
+     return listener[0] === eventType;
+  });
+
+  //invoke each event
+  for (var i = events.length - 1; i >= 0; i--) {
+    events[i][1].call();
+  }
+};
+
+EventEmitter.prototype.removeListener = function(eventType, callback) {
+  this.listeners = this.listeners.filter(function(listener) {
+    return !(listener[0] === eventType && listener[1] === callback);
+  });
+};
+
+EventEmitter.prototype.removeAllListeners = function(eventType) {
+  this.listeners = this.listeners.filter(function(listener) {
+    return listener[0] !== eventType;
+  });
+};
+
+EventEmitter.prototype.listenerCount = function(eventType) {
+  this.listeners = this.listeners.filter(function(listener) {
+    return listener[0] === eventType;
+  });
+
+  return this.listeners.length;
+};
+
+module.exports = EventEmitter;

fsp.js

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+var fs = require('fs');
+
+var fsp = {
+  readFile: function(file) {
+    return new Promise(function(resolve, reject) {
+      fs.readFile(file, 'utf8', function(err, data) {
+        if (err) {
+          reject('No Such File');
+        } else {
+          resolve(data);
+        }
+      });
+    });
+  },
+
+  writeFile: function(file, text) {
+    return new Promise(function(resolve, reject) {
+      fs.writeFile(file, text, 'utf8', function(err) {
+        if (err) {
+          reject('There was an error');
+        } else {
+          resolve(text);
+        }
+      });
+    });
+  },
+
+  appendFile: function(file, text) {
+    return new Promise(function(resolve, reject) {
+      fs.appendFile(file, text, 'utf8', function(err) {
+        if (err) {
+          reject('There was an error');
+        } else {
+          resolve(fsp.readFile(file));
+        }
+      });
+    });
+  }
+};
+
+module.exports = fsp;

index.js

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+// Warmups
+
+// 1.
+
+var p = new Promise(function() {
+  setTimeout(function() {
+    console.log("Hello Promise!");
+  }, 1000);
+});
+
+p.then(function(messsage) {
+  console.log(message);
+});
+
+// 2.
+
+var delayedMilliseconds;
+
+function sleep(delay) {
+  var start = new Date().getTime();
+  while (new Date().getTime() < start + delay);
+}
+
+function delay(milliseconds) {
+  delayedMilliseconds = milliseconds;
+
+  return new Promise(function() {
+    sleep(milliseconds);
+    console.log(milliseconds);
+  });
+}
+
+function countDown() {
+  if (delayedMilliseconds > 100) {
+    delayedMilliseconds -= 100;
+  } else {
+    delayedMilliseconds = "Done!";
+  }
+
+  delay(delayedMilliseconds);
+}
+
+delay(1000)
+  .then(countDown()) //=> 900
+  .then(countDown()) //=> 800
+  .then(countDown()) //=> 700
+  .then(countDown()) //=> 600
+  .then(countDown()) //=> 500
+  .then(countDown()) //=> 400
+  .then(countDown()) //=> 300
+  .then(countDown()) //=> 200
+  .then(countDown()) //=> 100
+  .then(countDown()); //=> Done!
+
+// 3.
+
+function square(num) {
+  return new Promise(function(resolve, reject) {
+    if (isNaN(num)) {
+      reject("'" + num + "' is not a number");
+    } else {
+      resolve(num * num);
+    }
+  });
+}
+
+var nums = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+nums = nums.map(function(i) {
+  return square(i);
+});
+
+Promise.all(nums)
+  .then(function(results) {
+    console.log(results);
+});
+
+// 4.
+
+function doBadThing(forRealz) {
+  return new Promise(function(resolve, reject) {
+    if (!forRealz) {
+      resolve("Yay!");
+    } else {
+      reject("Noooooo!");
+    }
+  });
+}
+
+// :) Path using reject handler
+doBadThing(0)
+  .then(function(results) {
+    console.log(results);
+  }, function(err) {
+    console.error(err);
+  });
+
+// :( Path using reject handler
+doBadThing(1)
+  .then(function(results) {
+    console.log(results);
+  }, function(err) {
+    console.error(err);
+  });
+
+// :) Path using .catch
+doBadThing(0)
+  .then(function(results) {
+    console.log(results);
+  })
+  .catch(function(err) {
+    console.error(err);
+  });
+
+// :( Path using .catch
+doBadThing(1)
+  .then(function(results) {
+    console.log(results);
+  })
+  .catch(function(err) {
+    console.error(err);
+  });
+
+
+
+// Create an Event Emitter from Scratch
+
+var Emitter = require('./event_emitter');
+// var Emitter = require('events');
+var emitter = new Emitter();
+
+function clickCallback() {
+  console.log('clicked');
+}
+
+function clickedAgainCallback() {
+  console.log('clicked again');
+}
+
+emitter.on('click', clickCallback);
+
+emitter.on('click', clickedAgainCallback);
+
+emitter.on('submit', function() {
+  console.log('submitted');
+});
+
+emitter.emit('click');
+
+emitter.removeListener('click', clickCallback);
+
+console.log("Removed the 'click' listener with the 'clickedAgainCallback', now there are " + emitter.listenerCount('click') + " 'click' event listeners");
+
+emitter.removeAllListeners('click');
+
+console.log("Removed all 'click' listeners, now there are " + emitter.listenerCount('click'));