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Author: jaydattpatel

053-Callback-Hell.js

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+/*
+author : Jaydatt Patel
+
+Callback hell is a phenomenon where a Callback is called inside another Callback. It is the nesting of multiple Callbacks inside a function. If you look at the design of the code, it seems just like a pyramid. Thus the Callback hell is also referred to as the ‘Pyramid of Doom’.
+
+Callback hell structurally is just a nesting of function calls inside a function. But, it becomes difficult to understand and keep track of the nesting once the size of the nesting is increased.
+*/
+
+function print(i){
+    console.log("This is call number "+i);
+}
+
+function fun(callback){
+
+    setTimeout(()=>{
+    
+        let i = 1 ;
+        callback(i); i++ ;
+        setTimeout(()=>{
+     
+      	    callback(i); i++;
+      	    setTimeout(()=>{
+        
+        	    callback(i); i++ ;
+        	    setTimeout(()=>{
+          
+          		    callback(i); i++ ;
+          		    setTimeout(()=>{
+            
+            		    callback(i); i++ ;
+            		    // .... and so on
+            		    
+          		    }, 800)
+        	    }, 700)
+      	    }, 500)
+        }, 300)
+    }, 100)
+}
+
+fun(print);

Import - Export Modules/Common JS - Export-Require Module/Arithmetic.js

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+/*
+author : Jaydatt Patel
+
+Common JS :
+module.exports : to export object.
+
+*/
+
+
+const PI = 3.14
+
+const add = (a,b) => {
+    console.log('Add : ',(a+b));
+}
+
+const sub = (a,b) => {
+    console.log('Sub : ',(a-b));
+}
+const mul = (a,b) => {
+    console.log('Mul : ',(a*b));
+}
+const div = (a,b) => {
+    console.log('Div : ',(a/b));
+}
+
+const info = (str = '')=>{
+    console.log('Calculator....!', str);
+}
+
+//export as function
+module.exports  = {PI, add, subtract : sub,mul};

Import - Export Modules/Common JS - Export-Require Module/Main.js

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+/*
+author : Jaydatt Patel
+
+Common JS :
+require('Filepath') : to get exported object
+*/
+
+// require('path') to import
+const operation = require('./Arithmetic.js'); 
+
+console.log(operation.PI);
+operation.add(2,6);
+operation.subtract(10,7);
+operation.mul(4,3);

Import - Export Modules/ES6 - Import-Export Module/Arithmetic.mjs

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+/*
+/*
+author : Jaydatt Patel
+
+ES6 Module : 
+
+File Name must be with .mjs extension : 
+    moduleFile.mjs
+    MainFile.mjs
+*/
+
+// Named inline Export Syntax:
+export const add = (a,b) => {
+    console.log('Add : ',(a+b));
+}
+const sub = (a,b) => {
+    console.log('Sub : ',(a-b));
+}
+const mul = (a,b) => {
+    console.log('Mul : ',(a*b));
+}
+const div = (a,b) => {
+    console.log('Div : ',(a/b));
+}
+
+const info = (str = '')=>{
+    console.log('Calculator....!', str);
+}
+
+//multiple named export
+export {sub,mul};
+
+//default single export
+export default info;

Import - Export Modules/ES6 - Import-Export Module/Main.mjs

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+/*
+author : Jaydatt Patel
+
+ES6 Module : 
+Modules are a fundamental concept in modern JavaScript development, allowing developers to organize code into separate files or modules. Each module encapsulates its variables, functions, and classes, avoiding naming conflicts and polluting the global scope. This modularity promotes code reusability, maintainability, and scalability in large-scale projects.
+
+File Name must be with .mjs extension : 
+    moduleFile.mjs
+    MainFile.mjs
+
+*/
+
+//single import
+// import {add} from './Arithmetic.mjs';  
+
+//multiple import
+// import {add,sub} from './Arithmetic.mjs'; 
+
+//multiple import with alise name
+// import {add as addition, sub as subtraction} from './Arithmetic.mjs'; 
+
+//import default only without {}
+// import info from './Arithmetic.mjs';
+
+//import default only with alise name and without {}
+// import infomation from './Arithmetic.mjs';
+
+//default and multiple import
+// import info, {add,sub} from './Arithmetic.mjs'; 
+
+//default and multiple import with alise name
+// import infomation, {add as additon, sub as subtraction} from './Arithmetic.mjs'; 
+
+//all import
+
+// require('path') to import
+import * as operation from './Arithmetic.mjs'; 
+
+operation.add(2,3);
+operation.sub(10,7);
+operation.mul(4,3);
+//  operation.div(20,2); //error: not fun. need to export to use
+operation.default();
+