How do you declare a namespace

Even though JavaScript lacks namespaces, we can use Objects, an IIFE (Immediately Invoked Function Expression) or let/const to create namespaces.

1. Using Object Literal Notation: Let's wrap variables and functions inside an Object literal which acts as a namespace. After that you can access them using object notation

javascript

1var namespaceOne = {
2  function func1() {
3  console.log("This is a first definition");
4  }
5  }
6  var namespaceTwo = {
7  function func1() {
8  console.log("This is a second definition");
9  }
10  }
11  namespaceOne.func1(); // This is a first definition
12  namespaceTwo.func1(); // This is a second definition

2. Using IIFE (Immediately invoked function expression): The outer pair of parentheses of IIFE creates a local scope for all the code inside of it and makes the anonymous function a function expression. Due to that, you can create the same function in two different function expressions to act as a namespace.

javascript

1(function () {
2  function fun1() {
3  console.log("This is a first definition");
4  }
5  fun1();
6  })();
7
8  (function () {
9  function fun1() {
10  console.log("This is a second definition");
11  }
12  fun1();
13  })();

3. Using a block and a let/const declaration: In ECMAScript 6, you can simply use a block and a let declaration to restrict the scope of a variable to a block.

javascript

1{
2  let myFunction = function fun1() {
3  console.log("This is a first definition");
4  };
5  myFunction();
6  }
7  //myFunction(): ReferenceError: myFunction is not defined.
8
9  {
10  let myFunction = function fun1() {
11  console.log("This is a second definition");
12  };
13  myFunction();
14  }
15  //myFunction(): ReferenceError: myFunction is not defined.

JavaScript Coding Exercise 36