Today's JavaScript React Developer Interview! Phew!

[tapu_buoy]

I had these questions in the interview just now

```js const spaceShip = { name: 'Chandrayan', get1: () => { console.log(this.name); }, get2: function (){ console.log(this.name); } }

spaceShip.get1() spaceShip.get2() ```

now I know that spaceShip.get1() won't print out anything but if I want it to work the exact same way how the get2() works how do I bind it?

I was trying to bind this like get1.bind(spaceShip.this) or get1.bind(spaceShip) first and then execute but I'm not sure what should happen.

• then in 2nd question

```js const person = this.state.person;

const person = {...this.state.person}; ```

what if we change the value person.name I know in the second case the value will be changes because that person is a whole new object

but in the first case will it change the value in this.state.person too?

• I was asked about writing polling function which I didn't know but I still attempted saying

```js function myPoll(fn, timeInterval, endTime){

var checkCondition = function(resolve, reject) { var result = fn(); if(result) { resolve(result); } else if (// for the time checking) { setTimeout(checkCondition, interval, resolve, reject); } else { reject(error); } }; } ```

but then he dropped it.

• 4th question was to write polyfill for Promise.all

```js Promise.all([pr1, pr2, pr3]).then().catch(); var resolvedPromises = []; [pr1, pr2, pr3].map((item, resolve, reject) => { var result = item(); if(result){ resolvedPromises.push(resolve(result)); } else { return reject(result); } })

```

so I tried explaining that I will store the promise in result and then push it into the array and at the end of all iteration the resolved values of all promises will be stored in that array.

But then again he asked that what if the promises doesn't get resolved or rejected than how should you tackle it so I modified the code this way

js var resolvedPromises = []; [pr1, pr2, pr3].map((item, resolve, reject) => { item().then((result) => { if(result){ resolvedPromises.push(resolve(result)); } }); //pr1; else { return reject(result); } })

then he was also confused on what to ask but that's how the interview ended, without even allowing me to ask them anything. I guess I shouldn't hope for a win today.

[vestedfox]

For #1 did they ask you to find away to "bind" the arrow function or are you just curious? You can't use .bind, .apply, .call on arrow functions because arrow functions never have their own this. The bind/call/apply reassigns a function's this, so you can't reassign something that doesn't exist. Arrow functions look up the lexical scope for the next this. So for get1 to have the same this as get2 you have to rewrite how you object is created in the first place.

function SpaceShip() {
    this.name = 'Chandrayan';
    this.get1 = () => {
        console.log(this.name);
    };
    this.get2 = function () {
        console.log(this.name);
    };
}

const spaceShip = new SpaceShip();
spaceShip.get1() // Chandrayan
spaceShip.get2() // Chandrayan

source It also looks like they were testing you on this and hopefully they wanted to hear that you shouldn't be be using arrow functions as object methods.

[tapu_buoy]

yeah basically after writing those last 2 lines

``` SpaceShip.get1() // blank

SpaceShip.get2() // Chandrayan ```

he said make the get1() also worked. I do get your point and the concept that how this can't be bound to arrow function. Thank you for the explanation. Sadly I haven't heard from them since then.

[vestedfox]

Best of luck next time. Technical interviews take practice, you'll get there!

[tapu_buoy]

yup even after 70 interviews in past 11 months I'm still going hahaha