ES6 vs Common Javascript in node js

learn about Es6 modules and common js, after this no doubt

1. ES6 modules are asynchronous loaded while,

2. Common js modules are synchronous loaded

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How to work with common js

const fs = require("fs")
const fd = rs.readFileSync("filename.txt", "utf-8")
console.log(fd)


// output: filename.txt (// the content will be displayed )

How to work with ES6

import fs from "fs"
const fd = fs.readFile("filename.txt", "utf-8")
console.log(fd)

// output: content of file will be displayed

// NOTE: FOR ES6 FILENAME SHOUDL BE 
FILENAME.mjs

Now forget about the common js module, in the Recent rends you only have to deal with ES6 module

1. Default method for one Function

    // add.js
    function add(a, b){
        return a+b;
    }
   
    export default add
   
    TODOD: index.mjs
    // TODO: FOR single acces
    import addNumber from "filename.mjs"
    console.log(addNumber(2,3));
   

2. More than one, function or component

   ```javascript function add(a, b){ return a+b; }

   function sub(a, b){ return a-b; }

// NOTE: THIS IS NOT AN OBJECT export { add, sub }

// IN index.mjs import {add} from "filename.mjs" import {sub} from "filename.mjs"

console.log(add(5,5)); console.log(sub(5,5));

3. **use as Method in Es6 module**

    ```javascript
    function add(a, b){
        return a+b;
    }

    function sub(a, b){
        return a-b;
    }


    // NOTE: THIS IS NOT AN OBJECT
    export {
        add, 
        sub
    }

    // IN index.mjs 
    // here we can use are export ,by diffent names as we want
    import {add as addTwoNumber} from "filename.mjs"
    import {sub as subTwoNumber} from "filename.mjs"

    console.log(addTwoNumber(5,5));
    console.log(subTwoNumber(5,5));

1. you can directly export the function(), variable and almost everything

    export function sub(a, b){
        return a-b;
    }
   
    export isUserLoggedIn = true;
   
    // and use them , in two ways...
    import {sub} from "filename.mjs"
    import {sub as DirectlySub} from "filename.mjs"
   
    console.log(`this is directly exported ${Sub(5,5)}`);
    console.log(`this is directly exported ${DirectlySub(5,5)}`);
   

2. you can import everything together,

    // filename.js
    function add(a, b){  
    // see if this function is not exported , than no issue 
        return a+b;
    }
   
    export function sub(a, b){  
    // only this function can be asscisible from outside
        return a-b;
    }
   
    // if you want import it
    import * as everyExportFunction from "filename.mjs"
    console.log(`every exported use in once ${everyExportFunction}`);
    console.log(everyExport);
   
    NOTE: 
    // and after that use (.),
    // you can access specific function or object
    console.log(`Subtrat ALl in Once : ${everyExportFunction.sub(40,40)}`);
   

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Thank youe!

CHIRAG KUMAR