Local Module: Export and Log
//// Writing Simple LOCAL Module
// Let's write simple logging module which logs the information,
// warning or error to the console.
// In Node.js, module is placed in separate JavaScript file.
// So, create a Log.js file and write the following code in it.
// name of file Log.js Copy
const log = {
info: function (info) {
console.log('Info: ' + info);
},
warning:function (warning) {
console.log('Warning: ' + warning);
},
error:function (error) {
console.log('Error: ' + error);
}
};
module.exports = log
// In the above logging module we created an object with
// three functions - info(), warning() and error().
// Ending assigned object to module.exports.
// module.exports in above ex exposes log object as a module.
// The module.exports is a special object which is included
// in every JS file in the Node.js application by default.
// Use module.exports or exports to expose a function,
// object or variable as a module in Node.js.
// Now, let's see how to use the above logging module in our application.
// Loading Local Module
// To use local modules in your application,
// you need to load it using require() function
// in the same way as core module.
// However, you need to specify the path of JavaScript file of the module.
const myLogModule = require('./Log.js');
myLogModule.info('Node.js started');
// In the above example, app.js is using log module.
// First loads logging module using require() function
// and specified path where logging module is stored.
// Logging module is contained in Log.js file in the root folder.
// So, we have specified the path './Log.js' in the require() function.
// The '.' denotes a root folder.
// The require() function returns a log object because logging
// module exposes an object in Log.js using module.exports.
// So now you can use logging module as an object and call
// any of its functions using dot notation
// e.g myLogModule.info() or myLogModule.warning() or myLogModule.error()
// Run the above example using command prompt (in Windows) as shown below.
C:\> node app.js
Info: Node.js started