@Kaushik1216 around 10 lines before the line you've added there are couple of todos that should point you to the needed changes.
Essentially what your code is doing is closing the modal always although we should keep the modal open when there's an error, mark the field as invalid and also render (inside the modal) the error message. In short you're changing the workflow here and introducing more clicks to complete a task if there's an error.

@dgrammatiko yes you are right ,so what can be best way to solve this issue .One way I think is ,when undesire folder name come,input field should become red and some text like invalid folder name above input field can be shown.

@dgrammatiko Please check this changes this will do as follow .

Please check this changes this will do as follow .

There are many more cases that Joomla (the PHP side) will not accept a name as valid, so somehow you need to check for all these.

Please check this changes this will do as follow .

There are many more cases that Joomla (the PHP side) will not accept a name as valid, so somehow you need to check for all these.

Ok ,then please provide me those cases I will do similiar things for all cases

Ok ,then please provide me those cases I will do similiar things for all cases

Dude if I have to do the research then I could as well do the PR...

Ok ,then please provide me those cases I will do similiar things for all cases

Dude if I have to do the research then I could as well do the PR...

Hmm, Ok then I will do research and find some more constraint

Error show if fiolder name already exist in directory as folder or file name

error show as follows

@dgrammatiko Is I am doing right for multiple case handling ?

AS I notice php side only accept folder name which contain only Alphanumeric,underscore(_) ,period ( . ) and hyphen ( - ).
if you include any other charachater other than this php remove all other character from folder name .
Problem is that if you have a folder name for example ss and you attempt to try create folder with name s@s then you not get any error and folder also not created because php remove @ from folder name and ss result new folder name which is already present their and bad thing is that user also get a success msg Folder created .

the only one error That I think should come from php side is when user not install INTL and ICONV php extension and writing non ascii character in folder name should we close modal for this error ?

Please rebase this to 4.3!

Lastly the media manager has the concept of adapters, ie supporting different online storage solutions (Amazon s3, Dropbox, etc). Therefore the checks here should cover all these options…

Please rebase this to 4.3!

I think rebaseing this pr with 4.3 will increse work more that also occure in my no search result pr .
So I am creating new Pr for 4.3 branch .Should I closed it then ?

closing by creating another Pr #39878 please refer this