assignment async nodejs

.gitignore

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+node_modules/

dummy.txt

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+Spicy jalapeno bacon ipsum dolor amet spare ribs pork loin meatball, pancetta doner venison sirloin pork t-bone sausage buffalo bresaola. Spare ribs buffalo prosciutto burgdoggen picanha.

emitterTest.js

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+var Emitter = require(`./eventEmitter`);
+// var Emitter = require('events');
+var emitter = new Emitter();
+
+function testAlpha() {
+  console.log(`alpha`);
+}
+
+function testBravo() {
+  console.log(`bravo`);
+}
+
+function testCharlie() {
+  console.log(`charlie`);
+}
+
+emitter.on(`event`, testAlpha);
+emitter
+  .on("event", testBravo)
+  .on(`event`, testCharlie);
+
+emitter.emit(`event`);
+
+emitter.removeListener(`event`, testAlpha);
+emitter.removeAllListeners(`event`);
+
+emitter.emit(`event`);

eventEmitter.js

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+var emitter = function() {
+  var events = {};
+
+  this.on = function(eventName, listener) {
+    if (events[eventName] == undefined) {
+      events[eventName] = [listener];
+    } else {
+      events[eventName].push(listener);
+    }
+    return this;
+  };
+
+  this.emit = function(eventName, ...rest) {
+    if (events[eventName] == undefined) {
+      return false;
+    } else if (rest.length == 0) {
+      for (var listeners in events[eventName]) {
+        events[eventName][listeners]();
+      }
+      return true;
+    } else {
+      for (var listeners in events[eventName]) {
+        events[eventName][listeners](rest);
+      }
+      return true;
+    }
+  };
+
+  this.removeListener = function(eventName, listener) {
+    if (events[eventName] != undefined) {
+      var index = events[eventName].indexOf(listener);
+      if (index != -1) {
+        events[eventName].splice(index, 1);
+      }
+    }
+    return this;
+  };
+
+  this.removeAllListeners = function(eventName) {
+    events[eventName] = undefined;
+    return this;
+  };
+};
+
+module.exports = emitter;

fileIO.js

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+//Take the Node.js fs modules and wrap in promises.
+var fs = require('fs');
+
+var fsp = {
+  readFile: function (path) {
+    return new Promise (function (resolve,reject) {
+      fs.readFile (path, 'utf8', (err,data) => {
+        err ? console.log(err) : resolve(data);
+      });
+    });
+  },
+  writeFile : function (path, data) {
+    return new Promise ( function (resolve, reject) {
+      fs.writeFile(path, data, function(err) {
+        if (err) {
+          reject(err);
+        } else {
+          fsp.readFile(path)
+            .then(function(data) {
+              resolve(data);
+            })
+            .catch(function(err) {
+              reject(err);
+            });
+        }
+      });
+    });
+  },
+  appendFile : function (path, data) {
+    return new Promise ( function (resolve, reject) {
+      fs.appendFile(path, data, function(err) {
+        if (err) {
+          reject(err);
+        } else {
+          fsp.readFile(path)
+            .then(function(data) {
+              resolve(data);
+            })
+            .catch(function(err) {
+              reject(err);
+            });
+        }
+      });
+    });
+  }
+}
+
+module.exports = fsp;

fspTest.js

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+var fsp = require(`./fileIO`);
+
+var writeData = "Spicy jalapeno bacon ipsum dolor amet spare ribs pork loin meatball, pancetta doner venison sirloin pork t-bone sausage buffalo bresaola. Spare ribs buffalo prosciutto burgdoggen picanha.";
+
+var appendData = "Cupcake ipsum dolor sit amet I love dragée donut candy. Jelly beans sweet roll jelly-o powder sweet. Jelly liquorice biscuit pastry.";
+
+fsp.readFile('lorem.txt')
+  .then(function(data) {
+    console.log("read data",data);
+  })
+  .catch(function(err) {
+    console.error("read err",err);
+  });
+
+fsp.writeFile('dummy.txt', writeData)
+  .then(function(res) {
+    console.log("write data",res);
+  })
+  .catch(function(err) {
+    console.error("write err",err);
+  });
+
+fsp.appendFile('lorem.txt', appendData)
+  .then(function(res) {
+    console.log("append data",res);
+  })
+  .catch(function(err) {
+    console.error("append err",err);
+  });

lorem.txt

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+Sweet sesame snaps marzipan cotton candy. Cake marshmallow toffee danish. Muffin toffee chocolate soufflé powder wafer chocolate marshmallow. Biscuit croissant gingerbread liquorice oat cake pie toffee.
+Cupcake ipsum dolor sit amet I love dragée donut candy. Jelly beans sweet roll jelly-o powder sweet. Jelly liquorice biscuit pastry.

package.json

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+{
+  "name": "assignment_async_nodejs",
+  "version": "1.0.0",
+  "description": "asynchronous node programming practice",
+  "main": "warmups.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/megantaylor/assignment_async_nodejs.git"
+  },
+  "keywords": [
+    "nodejs"
+  ],
+  "author": "megan taylor",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/megantaylor/assignment_async_nodejs/issues"
+  },
+  "homepage": "https://github.com/megantaylor/assignment_async_nodejs#readme"
+}

warmups.js

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+//These few warmups will get you started working with promises.
+
+//1. create a promise that logs  "Hello Promise!" after one second using .then
+var helloPromise = new Promise(function(resolve, reject) {
+  setTimeout(() => {
+    resolve(`Hello Promise!`);
+  }, 1000);
+});
+
+helloPromise.then(function(hello) {
+  console.log("helloPromise", hello);
+});
+
+//2. Create a delay(milliseconds) function that should return a promise thatresolves the value milliseconds after delaying for the specified number of milliseconds
+function delay(milliseconds) {
+  return new Promise((resolve, reject) => {
+    if (milliseconds > 0) {
+      resolve(milliseconds);
+    } else {
+      resolve(0);
+    }
+  });
+}
+
+function countDown(time) {
+  var output = time > 0 ? time : 'Done!';
+  console.log(output);
+  return delay(time - 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. The promise should reject if it is not passed a number. Map an array of integers 1 to 9 to an array of promises using the function. Use Promise.all to get the result of all of the promises in the array.
+
+var array = [1,2,3,4,5,6,7,8,9];
+
+function squared(num) {
+  return new Promise((resolve, reject) => {
+    if (isNaN(num)) {
+      reject(num);
+    } else {
+      resolve(num*num);
+    }
+  });
+}
+
+Promise.all(array.map(squared)).then(
+  results => {
+    console.log("squared", results);
+  },
+  error => {
+    console.log(error);
+  }
+);
+
+//4. Experiment with catch vs reject
+var doBadThing = forRealz => {
+  return new Promise( ( resolve, reject ) => {
+    if( forRealz ) {
+      reject('Nope');
+    } else {
+      resolve( 'Yay!');
+    }
+  });
+};
+
+doBadThing( true )
+  .then( result => console.log( result ))
+  .catch( error => console.error( error ));
+
+doBadThing( false )
+  .then( result => console.log( result ))
+  .catch( error => console.error( error ));
+
+doBadThing( false )
+  .then( result => {
+    console.log( result );
+    throw "ERROR!";
+  })
+  .catch( error => console.error( error ));
+
+doBadThing( true )
+  .then( result => {
+    console.log( result );
+  },
+    err => console.error( err )
+  );