Node JS Extra

• When you create a file in Node.Js, node actually wraps the content and puts it inside a function

  • example, if you create the below file

        // index.js
        console.log('Hello');
    

  • node wraps it as below

        // index.js
        function(exports, module, require, __filename, __dirname) {
            console.log('Hello');
            return module.exports;
        }
    

  • And hence you can use these params in your function and the module.exports gets returned. also the same reason why any variable that is created in this file is not global. since it in inside a function.

• To create a global values, you can add it to global object (but you shouldn't, that's the whole intention )

    global.name = 'Kota';
  

  • Example: the process, buffer, setTimeInterval, clearInterval, etc... are all part of this global object and that's why you can use it directly. In actual it is process is same as global.process. You can know this by printing the global console.dir(global, { depth:0 })

• Debugging node: using chrome developer tools

  • In VS Code: > node --inspect index.js and press ctrl+shift+p and select "Debug: Attach to node process" and then select your project
  • > node --inspect-brk index.js then open chrome://inspect in chrome or there are other tools also

• Node Basics

  • Event Emitters ( .emit(), .on() )
  • Timers (setTimeOut, setTimeInterval, clearTimeImmediate, etc....)
  • Buffer
  • Stream ( readable, writable, Transform & Duplex)
  • fs (File Service)
  • promises & async/await
  • process
  • os