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Hi I have started www.idontknowjavascript.com purely for educational purpose and want to share my knowledge and learn from you guys. Here I have provided many articles where I have tried explaining topics with simple examples. Also this is a place where we can share our queries, comment, questions etc with others.

I am Himanshu Sharma. I have 5+ years of Software development and IT experience and have worked on domains like CRM , ERP, Banking, Finance and Rail Transportation on various technologies like Javascript, NodeJs, AngularJs, Mongodb, ReactJs, Express Js, Mobile development etc.


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Come Closure in Javascript

What is a closure? If we want to derive a definition,we can say, A closure is a feature of Javascript where inner function has access to the outer (enclosing) function’s variables—scope chain. This scope chains means inner function has: access to its own scope (variables defined between its curly brackets and its parameters),access to the outer function’s variables and parameters, access to the global variables. Now we will look into it in detail. Consider following example
var globalVar = "xyz"; function outerFunc(outerArg) { var outerVar = 'Alex'; function innerFunc(innerArg) { var innerVar = 'Chris'; console.log("globalVar = " + globalVar); console.log("outerArg = " + outerArg); console.log("innerArg = " + innerArg); console.log("outerVar = " + outerVar); console.log("innerVar = " + innerVar); } innerFunc(456); } outerFunc(123); In this example, i…
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Javascript Hoisting Interview Question and Answers - 5

In this post,I have tried to cover all the types of possible interview questions and answers on hoisting. If you are not familiar with the hoisting, I would highly recommend you to go to my post on hoisting. Once you are comfortable with the topic, you can attempt these questions. Understanding the type of question will help you to answer. I have provided the hint after each question. All the answers are given at the end of the post.
//Question 1 console.log('bar:', bar) bar = 15 var foo = 1 console.log(foo, bar) var bar Hint: Basics of hoisting //Question 2 var foo = 5 console.log('foo:', foo) var foo; var bar = 10; var bar; console.log('bar:', bar) var baz = 10 var baz = 12 console.log('baz:', baz) Hint: Basics of hoisting //Question 3 function foo() { function bar() { return 5 } return bar() function bar() { return 10 } } console.log(foo()); Hint: Think what happens if two functions wit…
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Javascript Closure Interview Questions and Answers - 6

Here in the post, I have posted all the possible interview questions and answers on closure. If you are not familiar with the closure, I would highly recommend you to go to my post onclosure. Once you are comfortable with the topic, you can attempt these questions. All the answers are given at the end of the post.

//Question 1 function foo() { var a = 5 function bar() { console.log(a) } return bar; } var baz = foo() baz()
// Question 2 function outer(a) { var b = 2 function inner() { var c = 5 console.log(a * b * c) } return inner; } var multiply = outer(5) multiply()
// Question 3 const arr = [10, 20, 30, 40, 50] for (var i = 0; i < arr.length; i++) { setTimeout(function() { console.log('Index: ' + i + ', element: ' + arr[i]) }, 1000) }
// Question 4 for (var i = 0; i < 5; i++) { setTimeout(function(i) { return function() { console.log('The value of…
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