Add exercise-1

7-classes/exercises/exercise-1.js

@@ -0,0 +1,50 @@
+"use strict";
+//Your code does here
+
+class Book {
+  constructor(title, author, pages) {
+    this.title = title;
+    this.author = author;
+    this.#pages = pages;
+    this.copiesSold = 0;
+  }
+
+  get pages() {
+    return this._pages;
+  }
+
+  // private
+  set #pages(value) {
+    this._pages = value;
+  }
+
+  get copiesSold() {
+    return this._copiesSold;
+  }
+
+  set copiesSold(value) {
+    if (value < 0) {
+      throw new Error("Value can't be negative");
+    }
+    this._copiesSold = value;
+  }
+}
+
+const book = new Book("Who Moved My Cheese?", "Spencer Johnson", 96);
+console.log(book.title); //Who Moved My Cheese
+console.log(book.pages); //96
+try {
+  book.pages = 96;
+} catch (ex) {
+  console.log(ex.message);
+  //Cannot set property pages of #<Book> which has only a getter
+}
+console.log(book.copiesSold); //0
+book.copiesSold = 1;
+console.log(book.copiesSold); //1
+try {
+  book.copiesSold = -2;
+} catch (ex) {
+  console.log(ex.message); //Value can't be negative
+}
+console.log(book.copiesSold); //1