assignment_async_nodejs

README.md

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 # assignment_async_nodejs
 Async Node.js sprint
+Jared Gebel
+9/8/2017
+
+Promises, File Operations, and Event Emitters
+Promises
+index.js
+
+File Operations
+fspTest.js
+./data/lorem.txt
+./data/test.txt
+./lib/fsp.js
+
+Reverse Engineering Node.js Event Emitter
+./lib/emitter-mode.js
+emitter.js

data/lorem.txt

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+Lorem ipso, this is text.

data/test.txt

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+Hello!again!

emitterTest.js

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+var Emitter = require("./lib/emitter");
+var emitter = Emitter;
+
+var print = function(str) {
+  console.log(str);
+};
+
+emitter.on("click", function() {
+  console.log("click has fired");
+});
+
+emitter.on("pop", function() {
+  console.log("pop has fired");
+});
+
+emitter.emit("click");
+emitter.emit("pop");
+
+emitter.removeListener("click");
+
+emitter.emit("click");
+emitter.emit("pop");
+
+emitter.on("click", function() {
+  console.log("click has fired");
+});
+emitter.emit("click");

fspTest.js

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+var fs = require("fs");
+var fsp = require("./lib/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);
+  });

index.js

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+// 1. Create a promise that resolves the message "Hello Promise!" after 1 second
+var p = Promise.resolve("Hello Promise!");
+p.then(function(message) {
+  setTimeout(function() {
+    console.log(message);
+  }, 1000);
+});
+
+// 2. Create a function delay that returns a promise that resolves the value milliseconds after delaying for the specified number of milliseconds
+var delay = function(milliseconds) {
+  return new Promise(function(resolve, reject) {
+    setTimeout(function() {
+      resolve(milliseconds);
+    }, milliseconds);
+  });
+};
+
+var countDown = function(t) {
+  console.log(t);
+  return delay((t -= 100));
+};
+
+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); //=> Done!
+
+// 3. Create a function that accepts a number and returns a promise that resolves that number squared
+
+var squared = function(number) {
+  if (number !== "NaN") {
+    return number * number;
+  } else {
+    // can't get it to throw error beyond NaN
+    throw "Your input is not a number.";
+  }
+};
+
+var array = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+array = array.map(function(i) {
+  return Promise.resolve(squared(i));
+});
+
+Promise.all(array).then(
+  function(results) {
+    console.log(results);
+  },
+  function(err) {
+    console.log(err);
+  }
+);
+
+// 4. Create a function with signature doBadThing(forRealz)
+var doBadThing = function(bool) {
+  if (bool === false) {
+    return Promise.resolve("Yay!");
+  } else {
+    return Promise.reject("No");
+  }
+};
+
+var forRealz = true;
+doBadThing(forRealz)
+  .then(function(results) {
+    console.log(results);
+  })
+  .catch(function(err) {
+    console.log(err);
+  });
+
+var forRealz = false;
+doBadThing(forRealz)
+  .then(function(results) {
+    console.log(results);
+  })
+  .catch(function(err) {
+    console.log(err);
+  });

lib/emitter.js

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+var emitter = {
+  events: {},
+
+  on: function(eventType, callback) {
+    // If event type does not exist, create a new [eventType] array in events object
+    if (!this.events[eventType]) {
+      this.events[eventType] = [];
+    }
+
+    this.events[eventType].push(callback);
+  },
+  emit: function(eventType) {
+    var event = this.events[eventType];
+    if (event) {
+      event.forEach(function(callback) {
+        callback.call();
+      });
+    }
+  },
+
+  removeListener: function(eventType) {
+    var event = this.events[eventType];
+    event.shift();
+  },
+
+  removeAllListeners: function() {
+    this.events = {};
+  }
+};
+
+module.exports = emitter;

lib/fsp.js

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+var fs = require("fs");
+
+var _data;
+
+var fsp = {
+  readFile: function(path) {
+    return new Promise(function(resolve, reject) {
+      fs.readFile(path, "utf8", function(err, data) {
+        _data = data;
+        err ? reject(err) : resolve(data);
+      });
+    });
+  },
+
+  writeFile: function(path, data) {
+    return new Promise(function(resolve, reject) {
+      fs.writeFile(path, data, function(err, data) {
+        _data = data;
+        err ? reject(err) : resolve(data);
+      });
+    });
+  },
+
+  appendFile: function(path, data) {
+    return new Promise(function(resolve, reject) {
+      fs.appendFile(path, data, function(err, data) {
+        _data = data;
+        err ? reject(err) : resolve(data);
+      });
+    });
+  }
+};
+
+module.exports = fsp;

package.json

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+{
+  "name": "assignment_async_nodejs",
+  "version": "1.0.0",
+  "description": "Async Node.js sprint\r Jared Gebel\r 9/8/2017",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "https",
+    "url": "https://github.com/jaredjgebel/assignment_async_nodejs"
+  },
+  "author": "",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/jaredjgebel/assignment_async_nodejs"
+  },
+  "homepage": "https://github.com/jaredjgebel/assignment_async_nodejs#readme",
+  "dependencies": {
+    "events": "^1.1.1",
+    "fs": "0.0.1-security"
+  }
+}