Merge pull request #4 from enuber/generator

generator lesson

Author: enuber

app/index.js

@@ -1,65 +1,144 @@
-//classes
-
-// function Car(options) {
-//     this.title = options.title;
-// }
-// Car.prototype.drive = function() {
-//     return 'vroom';
-// };
-//
-// function Toyota(options) {
-//     Car.call(this, options);
-//     this.color = options.color;
-// }
-//
-//
-// Toyota.prototype = Object.create(Car.prototype);
-// Toyota.prototype.constructor = Toyota;
-//
-// Toyota.prototype.honk = function() {
-//     return 'beep';
-// };
-//
-//
-// const toyota = new Toyota({color: 'red', title: 'Daily Driver'});
-//
-// console.log(toyota.honk());
-// console.log(toyota.drive());
-// console.log(toyota.color);
-// console.log(toyota.title);
-
-//es6
-
-class Car {
-    //could do {title} instead of options and this.title = title;
-    constructor(options) {
-        this.title = options.title;
+//Generator
+// a generator can be entered and exited multiple times. We can return a value and then go right back into it
+//and keep going from the same location that we left.
+
+const colors = ['red', 'green', 'blue'];
+
+//for/of loop
+for (let color of colors) {
+    console.log(color);
+}
+
+//the *  makes this a generator
+function* shopping() {
+    //stuff on the sidewalk
+
+    // walking down the sidewalk
+
+    //go into the store with cash, //this is where we also reenter the generator
+    //with 'groceries' yield is a keyword that exits function and then when
+    //going back into the function we return to this place.
+    const stuffFromStore = yield 'cash';
+    //walking to laundrymat
+    const cleanClothes = yield 'laundry';
+    // walking back home
+    return [stuffFromStore, cleanClothes];
+}
+
+//stuff in the store
+//this doesn't actually go through the function
+const gen = shopping();
+//gives {'done': false} leaving our house, this is where we actually go into
+//the function.
+gen.next();
+//walked into the store at this point
+//walking through the store up and down the aisles
+//purchased our stuff
+// gives {'done': true} leaving the store with groceries
+gen.next('groceries');
+gen.next('clean clothes');
+
+
+function* colors() {
+    yield 'red';
+    yield 'green';
+    yield 'blue';
+}
+
+const myColors = [];
+for (let color of colors()) {
+    myColors.push(color);
+}
+
+myColors;
+
+
+const engineeringTeam = {
+    size: 3,
+    dept: 'Engineering',
+    lead: 'Jill',
+    manager: 'Alex',
+    engineer: 'Dave'
+}
+
+function* TeamIterator(team) {
+    yield team.lead;
+    yield team.manager;
+    yield team.engineer;
+}
+
+const names = [];
+for (let name of TeamIterator(engineeringTeam)) {
+    names.push(name);
+}
+
+names;
+
+//refractored
+const testingTeam = {
+    lead: 'Amanda',
+    tester: 'Bill',
+    //the Symbol.iterator gets used if it exists to use the generator it is
+    //pointing at to iterate over the object. the Symbol.iterator just teaches
+    //the for/of loop how to iterate over the object. Note the use of this as
+    //we are referring to the object that this generator is within.
+    [Symbol.iterator]: function* () {
+        yield this.lead;
+        yield this.tester;
     }
-    drive() {
-        return 'vroom';
+}
+
+const engineeringTeam = {
+    size: 3,
+    dept: 'Engineering',
+    lead: 'Jill',
+    manager: 'Alex',
+    engineer: 'Dave',
+    //could just be testingTeam by itself since it's key value is same
+    testingTeam: testingTeam,
+    [Symbol.iterator]: function* () {
+        yield this.lead;
+        yield this.manager;
+        yield this.engineer;
+        //this yield causes the for/of loop to iterate over the team.testingTeam
+        yield* this.testingTeam;
     }
 }
 
-//extends says we are grabbing a class Car and being able to use all it's methods
-//super() allows us to call Car.constructor() because they have the same name. If both had honk() methods, we could
-//declare super() inside the honk() method as well. We also have to pass super any info the Car.constructor()
-//may need as well.
-//Also to note you don't want to use destrucutring to pull off what you want, you need to have them all grouped
-//together within the object.
-class Toyota extends Car {
-    constructor(options) {
-        super(options);
-        this.color = options.color;
+const names = [];
+for (let name of engineeringTeam) {
+    names.push(name);
+}
+names;
+
+
+//tree
+
+class Comment {
+    constructor(content, children) {
+        this.content = content;
+        this.children = children;
     }
-    honk() {
-        return 'beep';
+    *[Symbol.iterator]() {
+        yield this.content;
+        for (let child of this.children) {
+            yield* child;
+        }
     }
 }
 
-const toyota = new Toyota({color: 'red', title: 'Daily Driver'});
-console.log(toyota.honk());
-console.log(toyota.drive());
-console.log(toyota.color);
-console.log(toyota.title);
+const children = [
+    new Comment('good comment', []),
+    new Comment('bad comment', []),
+    new Comment('meh',[])
+];
+
+const tree = new Comment('Great post!', children);
 
+const values = [];
+
+for (let value of tree) {
+    values.push(value);
+}
 
+values;

package.json

@@ -11,9 +11,12 @@
   "author": "Scott Bowler",
   "license": "ISC",
   "devDependencies": {
-    "babel-core": "^6.24.1",
+    "babel-core": "^6.25.0",
     "babel-loader": "^7.0.0",
+    "babel-polyfill": "^6.23.0",
     "babel-preset-env": "^1.4.0",
+    "babel-preset-es2015": "^6.24.1",
+    "babel-preset-stage-0": "^6.24.1",
     "express": "^4.15.2",
     "webpack": "^2.4.1",
     "webpack-dev-middleware": "^1.10.2"