Javascript Interview Questions ( Call, Bind and Apply ) - Polyfills, Output Based, Explicit Binding

#JavascriptInterview #Javascript #FrontendInterview

Javascript Interview Questions on Call, Bind and Apply Methods ( or Explicit Binding ) will be discussed in this video including its in Polyfills, Output Based Questions, this keyword etc.

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00:00 Intro
00:43 Ques 1 - What is Call?
02:54 Ques 2 - What is Apply?
03:38 Ques 3 - What is Bind?
04:53 Ques 4 - Output Based Question
06:10 Ques 5 - 'call' with function inside object
07:54 Ques 6 - Output Based Question
09:40 Ques 7 - Print all animals in Object
11:35 Ques 8 - Append Array with "apply"
13:30 Ques 9 - Using 'apply' to enhance built-in functions
14:59 Ques 10 - Bound Function
15:55 Ques 11 - Bind Chaining
16:48 Ques 12 - Fix the code
19:07 Ques 13 - Partial Application with bind
21:14 Ques 14 - Explicit Binding with Arrow Function
23:05 Ques 15 - Call Polyfill Implementation
26:54 Ques 16 - Apply Polyfill Implementation
28:18 Ques 17 - Bind Polyfill Implementation
32:14 Read Blog for this Video
32:23 Important Message 👀

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Special Thanks to our members -
Srinivas Ayyagari
Saikiran K

[ajitshaw]

Great Video 🤩, Yesterday a interviewer asked me to do a small function like this

const a = [1, 2, 3] // Output [1, 2, 3, 1, 2, 3]

I used spread method like this [...a, ...a]

Then he asked to do it in some other way, I could have used call and apply

a.push.call(a, ...a);
a.push.apply(a, a);

Thank you soo much for your hard work 😇🥰

[codeedict]

You can simpley destruct the array inside Math.max(...numbers) in order to get the same output. Apply isn't necessarily required but thanks for opening new doors, was helpful to understand a new usecase.

[juniorWeb]

one of the best videos I saw on the internet regarding polyfill for bind call and apply. Really really really thank you so much and god bless you, bro.

[sobhanthakur]

When I executed the same code, (given below), I got the output as undefined. Please explain
var status = 1;
setTimeout(() => {
const status = 2;
const data = {
status: 3,
getStatus() {
return this.status;
},
};

}, 0);

[hamzahusein]

Much needed video, especially wrt implementations using polyfills! Exanples and explanations on point 🚀

[prasangsinghal]

Amazing explanation.
Just a little correction, in polyfills implementation for call and apply, I think we need to call and return the return value also i.e. return context.fn(...args).

[hemangkoshiyar]

Function.prototype.myCall = function(context = {}, ...args){
if(typeof this !== 'function'){
throw new Error(this + ' is not callable')
}
context[this.name] = this;
context[this.name](...args)
}
We can also make our context object function key as our function name by doing this.

[nidhisharma]

At 15:40 sorry for pointing out but you did not clearly clarify why this would represent the global object here. The answer should be in non-strict mode javascript replace the `this` value to global object if it is assigned any value like null and undefined.

[kovendanragupathi]

Can you pls do a React specific interview questions, this is what lacks in all the best YouTube channels

[prateekgupta]

You deserve a subscribe. Keep up the good work bro.

[ashishroshan]

For pollyfill, can't we create call, apply and bind with Object protoype ?
According to your implementation, it will throw error if we attach these methods with object having a function.

[arijitroy]

Could you please make those videos in hindi language. It will be very easy to us. Please please make videos in easy hindi language..

[karthikeyasoft]

Polyfills understanding lot. How to think. Keep

[Rohitsingh]

People who are having issues with polyfills just run this, you will get it.
Function.prototype.myCall=function(context, ...args){
console.log("this ", this);
console.log("context ", context);
console.log("args ", args);
context.func=this;
console.log("context1 ", context);
context.func(...args)
}

[sunilkumar-zfdx]

#22:38 in the window object we have age, why it is displaying undefined.

Normally

var age=10;
let sample={
age: 20,
getage: ()=>{
console.log(this.age);
}
}
sample.getage();
Output will be :10

I'm still in confusion 😃 why it is displayed undefined

var age=10;
let sample={
age: 20,
getage: ()=>{
console.log(this.age);
}
}

let sample2= {
age: 30
};

sample.getage.call(sample2)
o/p: 10

[brajagopalmukherjee]

Bhaiya bht din video nhi ayi, how are you?
One Request bhaiya can u start react and next combined course which will cover basics to advanced with project also ? I was trying to learn, not able to focus what to learn

[ShubhamJain-qxtv]

In call polyfill what does context.fn = this; line represent

[evangriffith]

Thank you for the video! I have a question about #14 for anyone. For the getAgeArrow function, why doesn't the 'this' keyword contain the context of const age = 10 as declared on line 4?

[Ashish-_-]

Hi Piyush, just one thing, in the polyfills, I think we shouldn't add our function directly to the context object as it manipulates the original object. We can clone the object and then call our context.fn()

[Solo_playz]

Yes need video on prototypes of all objects.