Angular ngFor trackBy

[@sammyyou7712]

I used this in my project and its working perfectly. Thanks a ton Venkat sir.

[@rubbalbhusri4385]

In the last, at 11:22 time of the video, the headings ("Is Even" and "Is Last") got wrongly placed. A minor correction, I searched in the comments, it seems nobody noticed. Your videos are a great start for any beginner and a source of revision of concepts.

[@eugenenovikov671]

your English 50 times better than English of your Indian friends on freeCodeCamp and Udemy, thank u for clear speech

[@satheshkumar5906]

short, simple, and clear, thank you

[@dipakranjansahoo5722]

your tutorials are amazing,sir really i like it sir,i am ur fan

[@subhankarshrivastava5638]

one of the most talented person.

[@lifeislove9750]

Ya Thats Right

[@laughandtune]

thanks for all the pain/efforts you took, for this video.

[@SUMITKAUSHIK1000]

You are simply great Thanks alot... This is soooo generous that u have given the notes as well I mean I cannot explain I am soo greatful to you

[@niluniverse]

Its like people standing in Queue for iPhone in US / for Rajanikant movie in India. I m standing in queue for Venkat's Videos. I don't know my no in queue.

[@nirajrajpurohit1958]

This is awesome Thanks Sir. Really helpful for me. Please make a video to call the APIs in angular 2.

[@prakashgunjari1996]

Hi Venkat in the trackByEmpCode method, why do we need those parameters, index and employee. I tried running the code with out those parameters and it worked as expected, i.e with out refreshing the table elements. Infact I even made the return type as Void, it still worked. All the trackBy function would need is an empty method, to work, I think.

[@ousamaelidrissi5886]

Thanks a lot, keep going 👌

[@mohsinazamafridi8566]

Thanks for uploading this,it very nice,seen and implemented ,thanks @Venkat :) Be Blessed

[@dvishal23]

HI Venkat, Thank you for the tutorial. Your series on angular are great. I have a doubt regarding the trackBy, that if any value of one of the object changes, then it won't be updated on DOM, as we are not refreshing already loaded DOM. Could you help tackling such scenarios? Thank you Deep

[@krish_techaadimulam2243]

Ur Angular 2 videos r very useful for me thank u sir

[@kinglikeking]

Hi Sir, Your tutorials are amazing and very helpful. I have a small query in this lesson. You have said that when we trackby in ngfor, then the previous columns will not be loaded again. In ngFor we have a last attribute, that specifies the last element. when we initially have 4 elements, the fourth element is treated as the last element, but when we add the fifth element, then the boolean value for the fourth element representing last should be made it to false and the fifth element should say it as true Please confirm whether it will happen?

[@HemantSingh-pr7hd]

Nicely explained. Thanks.

[@shridharjjoshi]

hi can we use index property of ngFor directly for interpolation instead of declaring varible

[@kamdemkakengne]

Thank you so much Venkat

[@mamdouhemara7299]

hey Venkat, i have the following question but in ASP.NET Web API what if we want to make the response be like TotalCount, TotalPages and Entity Details so if we used HttpResponseMessage or IHttpActionResult the response will be Entity Details and other details like StatusCode Header etc so where we can add TotalCount and TotalPages?? also if we added the TotalCount and TotalPages in Class called XResponse along with the Entity Properties and make the Method return type XResponse in this case we can not control in the Status Code or Headers or anything that related to HttpResponseMessage?

[@ymtan]

Dear Venkat, I would like to ask for the trackByEmpCode method how come you didn't pass any value for both the index and employee parameters from trackBy:trackByEmpCode specified with the ngFor directive ??? trackByEmpCode(index:number, employee: any): string { return employee.code; }

[@sagardeshmukh6120]

It is because, the trackBy function takes the index and the current item as arguments by default. Also, it needs to return the unique identifier for the current item.

[@selvarajmunuswamy3656]

empty method also return the same value like not reloading the trackByEmpCode() { } Not sure about those two parameter, why we have to use that trackByEmpCode(index:number, employee:any):string { return employee.code; } please explain Thanks in advance

[@monakolanji]

Hi Venkat, just for testing I have removed the trackByEmpCode function from class and trackBy:trackByEmpCode from html and then build and hit F5. It gives the same result even after I removed them. Can you please explain?

[@secretsquirrel5566]

You Sir, are magnificent!

[@anilvadlamudi2039]

Hi Sir, Do you have your Azure videos, I would like to learn azure from your videos. Are you providing online course or if you have videos, I would like to buy your Azure videos.

[@abhishektiwari9200]

Although the tr elements are not being recreated every time after trackBy, but the selector tag of the component is getting refreshed. So indirectly the table is also being recreated ?

[@antonoreshko9551]

Hello, your tutorials are amazing! But your old tutorials (Java Script, Entity Framework etc.) used Web Forms. Today it's not longer relevant. Can you do similar tutorials using newer technologies (MVC, Web Api)

[@RachitJain4U]

Awesome :) Thanks :)

[@TheINTERLECT1]

Why aren't you passing in the parameters when you are calling the trackByEmpCode function in the view template? Its expecting a number and an employee object. How does angular prevent the tearing down of the row if it does not have the arguments?

[@shaun2099]

If you change Tom to Tomy in method getEmployees(), will angular identify the change to the item? Of course, angular will show Tomy when click the button, that means trackby not only identify the change by employee.code, please explain!!!

[@EnzoQuartana]

Always very good

[@yele2652]

thanks, sir. what happens if i update record - the employee code hasnt changed , therefor its record wont be uploaded again and data wont be updated on screen?

[@dyldvine]

The trackByEmpCode function has two parameters. But when you specify this function in the ngFor directive, you do not pass any arguments to the parameters. I don't understand why that works. Where/how does it get the values passed into the parameters?

[@sauravtanwer8435]

Sir your voice is same as the professor in Money Heist :) .

[@techie2903]

trackByEmpCode(index:number, employee:any) method has some parameter when declaring it. So why parameters are not passed when applying it in the ngFor directive.

[@sachinchakravarthys1807]

Does trackBy is the keyword of ngfor ?

[@HK-sw3vi]

thank you good sir! was looking for that i = index part

[@satyaprakashsingh8051]

HI, I am trying to follow the same step but can not able to get the map(). I have already imported the "import 'rxjs/add/operator/map'" but it does not work for me.

[@pradeepsharma2163]

this is little confusing i could see trackByEmpCode is a method that need index,employee to be passed when called. but while calling trackByEmpCode using trackBy:trackByEmpCode' we are not passing either index or employee parameter. could you please explain it

[@DecentProgrammer]

thanks for the video sir

[@semikolon4229]

Very Helpful.

[@nischalaks9838]

Hi sir, great vedios and your explaination is too good. Please make some vedios on "non coding courses" which will be helpful for people who doesn't want to code. And apt for trendy non coding courses( I mean to say other than programming languages) which will be helpful for ladies as well. I hope il get a reply from you sir. Thanks in advance

[@amitsunnysingh]

How trackBy will come to know that we want to track with employee code not with any other property If code and name has the same value string, then how its gonna track that

[@TheShakthirvd]

Because in trackByEmpCode you are returning empcode to trackBy.

[@juturisharon3075]

pls make a video to call the apis in angular

[@alankardasare4732]

why index as parameter and returning code, why not code as parameter and returning the code?

[@maheshippili7918]

How to modify dom of an attribute when it clicked, that is in a ngFor loop

[@subbaramireddygouru3314]

please upload all videos

[@pitchaipillai519]

could you please provide more videos with less interval between videos... waiting ..

[@tanhoa1517]

the video image is too poor, you need to fix it more