Add TypeScript code examples in src/01-intro/08-typescript.js and src/01-intro/08-typescript.ts

Author: loiane

src/01-intro/08-typescript.js

@@ -0,0 +1,17 @@
+// Path: src/01-intro/08-typescript.ts
+var myName = 'Packt';
+// myName = 10; // commented to avoid error
+/* Type inference */
+var age = 20; // number
+var existsFlag = true; // boolean
+var language = 'JavaScript'; // string
+var favoriteLanguage;
+var langs = ['JavaScript', 'Ruby', 'Python'];
+favoriteLanguage = langs[0];
+function printName(person) {
+    console.log(person.name);
+}
+var john = { name: 'John', age: 21 };
+var mary = { name: 'Mary', age: 21, phone: '123-45678' };
+printName(john);
+printName(mary);

src/01-intro/08-typescript.ts

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+// Path: src/01-intro/08-typescript.ts
+
+let myName = 'Packt';
+// myName = 10; // commented to avoid error
+
+/* Type inference */
+let age = 20; // number
+let existsFlag = true; // boolean
+let language = 'JavaScript'; // string
+
+let favoriteLanguage: string;
+let langs = ['JavaScript', 'Ruby', 'Python'];
+favoriteLanguage = langs[0];
+
+/* Interfaces as type */
+interface Person {
+  name: string;
+  age: number;
+}
+
+function printName(person: Person) {
+    console.log(person.name);
+}
+  
+const john = { name: 'John', age: 21 };
+const mary = { name: 'Mary', age: 21, phone: '123-45678' };
+printName(john);
+printName(mary);
+
+/* Interfaces as OO */
+interface Comparable<T> {
+  compareTo(b: T): number;
+}
+
+class MyObject implements Comparable<MyObject> {
+  age: number;
+  
+  constructor(age: number) {
+    this.age = age;
+  }
+
+  compareTo(b: MyObject): number {
+    if (this.age === b.age) {
+      return 0;
+    }
+    return this.age > b.age ? 1 : -1;
+  }
+}
+
+/* Enums */
+enum Compare {
+  LESS_THAN = -1,
+  BIGGER_THAN = 1,
+  EQUALS = 0
+}
+
+function compareTo(a: MyObject, b: MyObject): number {
+  if (a.age === b.age) {
+    return Compare.EQUALS;
+  }
+  return a.age > b.age ? Compare.BIGGER_THAN : Compare.LESS_THAN;
+}
+
+/* Type aliases */
+type UserID = string;
+type User = {
+  id: UserID;
+  name: string;
+}