• Saturday , 30 May 2020

Top 10 JavaScript Interview Questions

Code Canyon



Top 10 commonly Asked JavaScript Interview Questions and its possible answers.

Original source

3d Ocean

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35 Comments

  1. Keshav Sharma
    December 18, 2018 at 12:47

    2morow is my interview as a web dev. intern, hopefully i will make it 🙂

  2. Gee Kay
    December 18, 2018 at 12:47

    Man I feel stupid. I keep trying to learn JS, but it just seems bottomless.

  3. Ravi Kumar Grandhi
    December 18, 2018 at 12:47

    It is very helpful for interviews.

  4. Kaidie Su
    December 18, 2018 at 12:47

    Got the interview today, exactly the second question be asked. I hoped earlier to see this video! 😭

  5. Imran Rafiq Rather
    December 18, 2018 at 12:47

    Hi, Nice tutorial!
    I have a question that is troubling me a lot;

    At 7:50 ,
    const c; // Is c by default set to undefined or not?

    becuase when i am directly doing just after writing const c;

    console.log(c); // error I am getting: (Uncaught SyntaxError: Missing initializer in const declaration)

    Why so?

    And when I tried the same with let:

    let c;
    console.log(c);// undefined I got!

    Again when I myself initialize like below:

    const c=undefined;
    console.log(c); //undefined is the answer

    Kindly help in this regard!

    And thank you very very much for your awesome awesome videos.

    Humble Request:
    Please create a video series on react-redux saga, where you develop a full fledged website components in react-redux!
    I already completed your react-redux starter course! Please create some advanced stuff 🙂

  6. Andreas Jackson
    December 18, 2018 at 12:47

    89 people don't know Javascript.

  7. Prasada Shetty
    December 18, 2018 at 12:47

    Can you please create a video on document.getSelection

  8. Rajesh Chaubey Ui-Developer
    December 18, 2018 at 12:47

    Thanks for answering all questions

  9. C. Diaz
    December 18, 2018 at 12:47

    Great videos

  10. JH5280
    December 18, 2018 at 12:47

    Great explanations!

  11. Nikhil Goyal
    December 18, 2018 at 12:47

    When I run this code, both console statements output undefined, as opposed to what is explained in the video.

    let x=function(){
    if(true){
    console.log(v);
    console.log(l);
    var v=2;
    let l=1;
    }
    }

    x();

  12. sudhansu choudhary
    December 18, 2018 at 12:47

    @techsith one more noticeable difference, can surprise a few folks, i.e., when we declare a variable using let in global scope, the variable doesn't become a property of the global object whereas variables declared with var would be present as a property on the global object..

    var t = "Property On Global object";

    let x = "Not a property on global object";

    console.log(t); //"Property On Global object"

    console.log(window.t); //"Property On Global Object"

    console.log(x); //"Not a property on global object"

    console.log(window.x); //undefined

    Although both the variables can be accessed by inner scopes to the global and at the global scope itself, but the variable declared with let keyword won't be available as a property to the global object.

    For more, check – http://www.ecma-international.org/ecma-262/6.0/#sec-global-environment-records

  13. ShyneBrady
    December 18, 2018 at 12:47

    Some questions from my interviews:
    1. How would you describe that even bubbling works?
    2. calc(1)(2) returns 3. How would you write that function?
    3. What do you know about ES7?
    4. What is a callback function and how would you write it?
    5. Adding an array to another array without using push. How would you do it?

  14. casey brinegar
    December 18, 2018 at 12:47

    Null can be sent from an event

  15. Mohamed Abdelaziz
    December 18, 2018 at 12:47

    Thanks

  16. waetech solutions
    December 18, 2018 at 12:47

    Thank yo sir this was very helpful.

  17. Anatolia Dayim
    December 18, 2018 at 12:47

    1 Explain let,var and const variable declaration and explain their scope .what is strict mode?

    2 What are callbacks and callback hell in javascript . What are higher order functions?

    3 What is hositing in javascript ?

    4 What are prototypes and explain Prototypal inhertiance ?

    5 What are Closures in javascript?

    https://truetocode.com/top-10-javascript-interview-questions-concepts-every-javascript-developer-should-know/839/

  18. Silenc3
    December 18, 2018 at 12:47

    this is so good and a lot of help. thank you!

  19. sarita jha
    December 18, 2018 at 12:47

    Hi Techsith could you please explain following code ?? I have been asked in one of the interviews for the output –

    function parent() {
    var numOne = 1;
    function child(){
    var numTwo = 2;
    }
    console.log("numOne and numTwo are ", numOne , numTwo );
    }
    parent();

    Thanks in advance

  20. Weijuan Zhou
    December 18, 2018 at 12:47

    Really helpful. Thanks a lot!

  21. Tianchi Xu
    December 18, 2018 at 12:47

    A const declaration must have an explicit initialization
    If you want a const with the undefined value, you'd have to declare const c = undefined to get it.
    const c alone will throw a SyntaxError: Missing initializer in const declaration
    Reassign will throw TypeError: Assignment to constant variable.

  22. Rodney James
    December 18, 2018 at 12:47

    Nice video to augment all of the other great videos you create. One thing I noticed, and this is a technicality. When describing the difference between 'let' and 'var', you state that the definition of a 'var' is hoisted, but not the value. What you meant to say (I am certain) is that the DECLARATION is hoisted and not the definition. This is an important clarification that needs to be made. Keep up the good work!!

  23. Remi Vledder
    December 18, 2018 at 12:47

    @techsith Thanks for the informative explanation. Regarding the difference between let and const, what is the purpose of 'if (true) { … }'. Is to mimic a function scope?

  24. Simple Developer
    December 18, 2018 at 12:47

    who got udemy ad too ?

  25. nickwalshblog
    December 18, 2018 at 12:47

    thanks for vid learnt lots

  26. ram kasani
    December 18, 2018 at 12:47

    Plz upload series on angular6

  27. kartik garasia
    December 18, 2018 at 12:47

    i they asked me 3 same questions.. just completed phone interview.. and it went not that bad thanks to you 🙌🏻

  28. Carol Li
    December 18, 2018 at 12:47

    Thanks for the great videos! Just wanna ask is the questions and answers have a PDF version? Many thanks!

  29. Gaurav Popli
    December 18, 2018 at 12:47

    Thank you for the videos 🙂

  30. Nikhil Chugh
    December 18, 2018 at 12:47

    where do we need to place the refrence table file on nformatica server?

  31. Shahriar Ahmad
    December 18, 2018 at 12:47

    very helpfull video, thanks

  32. Subrat Kumar
    December 18, 2018 at 12:47

    can you tell me how we will prove that javascript is a scripting language?

  33. Alok Deshwal
    December 18, 2018 at 12:47

    Only function object has "prototype" property not all object.

  34. Rodney James
    December 18, 2018 at 12:47

    You create very informative videos with examples that serve to illuminate rather than confuse the concepts at hand. Keep up the good work.

  35. Thomas Petersohn
    December 18, 2018 at 12:47

    is this a joke or are These Questions for real? ;))

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