added some exercise bits to step 2.1

step2-01/src/spread/index.ts

@@ -1,6 +1,6 @@
 // Destructuring
-var [x, y, ...rest] = [1, 2, 3, 4];
-console.log(x, y, rest); // 1,2,[3,4]
+var [a, b, ...rest] = [1, 2, 3, 4];
+console.log(a, b, rest); // 1,2,[3,4]
 
 // Array assignment
 var list = [1, 2];
@@ -11,5 +11,14 @@ console.log(list); // [1,2,3,4]
 const point2D = { x: 1, y: 2 };
 const point3D = { ...point2D, z: 3 };
 
+// Concat two objects
+const obj1 = { x: 1 };
+const obj2 = { y: 2 };
+
+const obj3 = { ...obj1, ...obj2 };
+
+// Destructuring object
+const { x } = obj3;
+
 // adding an export to turn this into a "module"
 export default {};

step2-01/src/types/index.ts

@@ -26,12 +26,16 @@ type Specific2 = {
 };
 
 // composition
-type typeofObj = {
+type TypeOfObj = {
   foo: string;
   bar: number;
-  obj: Specific1;
+  obj1: Specific1;
+  obj2: Specific2;
 };
 
+// Get types by property
+type Obj1Type = TypeOfObj['obj1'];
+
 // union, intersection
 type Union = Specific1 | Specific2;
 type Intersection = Specific1 & Specific2;