created Promises, event listeners and file operations

README.md

@@ -1,2 +1,26 @@
-# assignment_async_nodejs
-Async Node.js sprint
+# Building with Async Node.js (promises, event emitter...)
+
+I this project I built promise-based interfaces. I used promises to write promise based versions of common Node.js fs module functions. Finally, `emitter.js` I created my own implementation of the Node.js EventEmitter and implemented it so it can be switched out with the core Node.js version!
+
+
+
+## Getting Started
+
+If you have [installed node](https://nodejs.org/en/download/) on your computer, type the following commands
+
+```
+$ node example.js
+```
+
+If you want to check statistics of other users run also the following lines after:
+
+
+
+## Authors
+
+* **Dariusz Biskupski** - *Initial work* - https://dariuszbiskupski.com
+
+
+## Acknowledgments
+
+This assignment is created for [Viking Code School](https://www.vikingcodeschool.com/)

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. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

data/test.txt

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+Hello!Hello again!

emitter.js

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+// var Emitter = require('./event');
+
+var Emitter = require('events');
+var emitter = new Emitter();
+
+var callback1 = function callback1() {
+  console.log('The first event occured!');
+}
+
+var callback2 = function callback2() {
+  console.log('A second Event!!');
+}
+emitter.on('event', callback1 )
+        .on('event', callback2 );
+emitter.emit('event');
+
+emitter.removeListener('event', callback1 );
+console.log(emitter);
+
+emitter.removeAllListeners('event');
+console.log(emitter);

event.js

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+
+var Emitter = function() {
+  this._events ={};
+  this.on = function (eventType, callback) {
+    if (this._events[eventType]) {
+      this._events[eventType].push(callback);
+    } else {
+      this._events[eventType] = [callback];
+    }
+    return this;
+  };
+  this.emit = function(eventType) {
+    this._events[eventType].forEach( function(callback) {
+      return callback();
+    })
+  };
+  this.removeListener = function(eventType, callback) {
+    var idx;
+    this._events[eventType].forEach( function(callback_iter, index) {
+      if (callback_iter === callback) {
+        idx = index
+      }
+    })
+    this._events[eventType].splice(idx, 1);
+  };
+  this.removeAllListeners = function(eventType) {
+    delete this._events[eventType];
+  }
+}
+
+
+
+module.exports = Emitter;

file_op.js

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+
+var fsp = require('./fsp');
+
+fsp.readFile('./data/lorem.txt')
+  .then(function(data) {
+    // Outputs the file data
+    console.log(data);
+  })
+  .catch(function(err) {
+    console.error(err);
+  });
+
+fsp.writeFile('./data/test.txt', 'Hello!')
+  .then(function(res) {
+    // Outputs the file data
+    // after writing
+    console.log(res);
+  })
+  .catch(function(err) {
+    console.error(err);
+  });
+
+fsp.appendFile('./data/test.txt', 'Hello again!')
+  .then(function(res) {
+    // Outputs the file data
+    // after appending
+    console.log(res);
+  })
+  .catch(function(err) {
+    console.error(err);
+  });

fsp.js

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+
+var fs = require('fs');
+
+//
+// fsp.writeFile('./data/test.txt', 'Hello!')
+//   .then(function(res) {
+//     // Outputs the file data
+//     // after writing
+//     console.log(res);
+//   })
+//   .catch(function(err) {
+//     console.error(err);
+//   });
+
+module.exports = {
+  readFile:  function (path) {
+                return new Promise((resolve, reject) => {
+                  fs.readFile(path, 'utf8', (err, data) => {
+                    err ? reject(err) : resolve(data);
+                  })
+                })
+              },
+  writeFile: function (path, text) {
+                return new Promise((resolve, reject) => {
+                  fs.writeFile(path, text,'utf8', (err, data) => {
+                    err ? reject(err) : resolve(data);
+                  })
+                })
+              },
+  appendFile: function (path, text) {
+              return new Promise((resolve, reject) => {
+                fs.appendFile(path, text, 'utf8', (err, data) => {
+                  err ? reject(err) : resolve(data);
+                })
+              })
+            }
+
+};

package.json

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+{
+  "name": "assignment_async_nodejs",
+  "version": "1.0.0",
+  "description": "Async Node.js sprint",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/Visiona/assignment_async_nodejs.git"
+  },
+  "author": "",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/Visiona/assignment_async_nodejs/issues"
+  },
+  "homepage": "https://github.com/Visiona/assignment_async_nodejs#readme"
+}

promise.js

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+
+var p = Promise.resolve("Hello Promise!");
+
+p.then( function(message) {
+  console.log(message);
+});
+
+
+var delay = function(milliseconds) {
+  return new Promise((resolve) => {
+    setTimeout(function() {
+      resolve(milliseconds);
+    }, milliseconds);
+  });
+}
+
+function countDown (message) {
+  console.log(message);
+  return message - 100;
+}
+
+var square = function(number) {
+  return new Promise((resolve, reject) => {
+    resolve(number * number);
+    if (number == undefined) {
+      reject('No Number');
+    }
+  });
+}
+
+var int = [1,2,3,4,5,6,7,8,9];
+var num = int.map( function(i) {
+  return square(i);
+})
+
+Promise.all(num).then(function(results) {
+  console.log(results);
+})
+
+var doBadThing = function(forRealz){
+  return new Promise((resolve, reject) => {
+    if (forRealz == false) {
+      resolve('Yay');
+    } else {
+      reject('rejected');
+    }
+  });
+}
+
+doBadThing(4).then( function(result) {
+                  console.log(result);
+                })
+              .catch( function(err){
+                console.error(err);
+              });
+
+doBadThing(true).then(function() {
+  console.log('I am  falsy');
+}, function() {
+  console.error('I am truthy');
+})
+
+doBadThing(0).then( function(result) {
+                console.log(result);
+                throw "Boom Boom Boom! Finito!!";
+              })
+            .catch( function(err){
+              console.error(err);
+            });
+
+
+
+delay(1000)
+  .then(countDown) //=> 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);