isNullOrEmpty method returns true if input is empty string or null
Install the package using npm :
npm install test-da-package --save
Then, require the package and use it:
[Comment: To check if this usage is proper]
var a = require('test-da-package');
console.log(a.isNullOrEmpty("")); // true
console.log(a.isNullOrEmpty("Hello World")); // false