Step 2-01 updates

step2-01/demo/src/async/index.ts

@@ -3,10 +3,10 @@ async function fetchSomething() {
   return await response.text();
 }
 
-// Async functions always returns Promise
+// Async functions always return a Promise
 fetchSomething().then(text => {
   console.log('hello ' + text);
 });
 
-// adding an export to turn this into a "module"
+// adding an export turns this into a "module"
 export default {};

step2-01/demo/src/generics/index.ts

@@ -19,5 +19,5 @@ function reverse<T>(arg: T[]): T[] {
   return arg;
 }
 
-// adding an export to turn this into a "module"
+// adding an export turns this into a "module"
 export default {};

step2-01/demo/src/interfaces/index.ts

@@ -1,22 +1,32 @@
+// Interface for an object or class
 interface Car {
   make: string;
   model: string;
 }
 
 class MyCar implements Car {
-  make: 'Honda';
-  model: 'Accord';
-}
+  make: string;
+  model: string;
 
-const myCar: Car = {
+  constructor(make: string, model: string) {
+    this.make = make;
+    this.model = model;
+  }
+}
+const myCar1: Car = new MyCar('Honda', 'Accord');
+
+const myCar2: Car = {
   make: 'Honda',
   model: 'Accord'
 };
 
-// Interface as Functions
+// Interface for a function
 interface InterestingFn {
   (someArgs: string): number;
 }
+const interesting: InterestingFn = (someArgs: string): number => {
+  return Number(someArgs);
+};
 
 // adding an export to turn this into a "module"
 export default {};

step2-01/demo/src/modules/index.ts

@@ -1,10 +1,10 @@
 // These are named imports from a file relative to this file
 import { namedConst, namedFn, namedObj, namedConstBracket } from './named';
 
-// We can even apply an alias to the named constant
+// We can even give an alias to the named constant
 import { namedConst as c } from './named';
 
-// These are the same instances of the named imports, but gets imported all at the same time under a single object
+// These are the *same instances* of the named imports, but they all get imported inside a single object
 import * as named from './named';
 
 // Print out the exports
@@ -14,12 +14,15 @@ console.log(namedFn());
 console.log(namedObj);
 console.log(namedConstBracket);
 
-// Print out exports through module level import
+// Print out exports from module level import
 console.log(named.namedConst);
 console.log(named.namedFn());
 console.log(named.namedObj);
 console.log(named.namedConstBracket);
 
+// The named and module-level imports reference the same object instances
+console.log(namedObj === named.namedObj); // true
+
 // Default import can be named anything we want as the consumer
 import DefaultClass from './default';
 import Foo from './default';

step2-01/demo/src/spread/index.ts

@@ -1,6 +1,6 @@
 // Destructuring
 var [a, b, ...rest] = [1, 2, 3, 4];
-console.log(a, b, rest); // 1,2,[3,4]
+console.log(a, b, rest); // 1 2 [3,4]
 
 // Array assignment
 var list = [1, 2];
@@ -20,5 +20,5 @@ const obj3 = { ...obj1, ...obj2 };
 // Destructuring object
 const { x } = obj3;
 
-// adding an export to turn this into a "module"
+// adding an export turns this into a "module"
 export default {};

step2-01/demo/src/types/index.ts

@@ -47,13 +47,18 @@ let choose1 = <Specific1>{ common: '5' };
 type CatStatus = 'alive' | 'dead' | 'both';
 
 // Classes
-class Animal {}
+class Animal { }
 
 // Illustration purposes only
 // In real apps, avoid inheritance if possible
 // noted exception: React.Component with react@<16.8.0
-class Cat extends Animal {}
-class Dog extends Animal {}
+class Cat extends Animal { }
+class Dog extends Animal { }
 
-// adding an export to turn this into a "module"
+// Any Type - avoid if possible
+let mystery: any = "I don't like the person who will be maintaining this code";
+mystery = 2;
+mystery = () => 3;
+
+// adding an export turns this into a "module"
 export default {};