Warp function outside with error handling

Question

I've node application which users can provide own function and according to some URL path which the user give I invoke this function,the problem in case of error the request doesnt stops so I want somehow to get the error in the caller (if any) in stops the response,what is recorded to do in this case ?

lest say that this is the function which the user provided,in case we have the file in the directory this is working fine

delete: function (req,res,Path) {

    var fileRelPath = 'C://'+ Path;
    fs.unlinkSync(Path);
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end("File was deleted");
},

I call to this function from other module to invoke the function

plugin[fnName](req, res, Path);

In case the file doesn't exist I got error and the process call not stops... should I maybe check somehow after the above invoke code if res.end() was called,if not to end it explicit,if yes how to check if it ended.

I mean something like

plugin[fnName](req, res, Path);
if(res.end was not invoked)
res.end("error occurred"  )
maybe to provide additional data somehow about the err ..

Answer 1

You can try the following. But The function has to be synchronous, like the example you provided. Otherwise try..catch won't work.

var error;
try{
  plugin[fnName](req, res, Path);
}
catch(e){
  error = e
}

if(!res.headerSent){
  res.send(error);
}

For Async operations you have to rewrite your function in node callback style:

deleteAsync: function (req,res,Path,done) {
    var fileRelPath = 'C://'+ Path;
    fs.unlink(Path, function(err){
       if(err)
         return done(err)
       res.writeHead(200, { 'Content-Type': 'text/plain' });
       res.end("File was deleted");
    });


},

then call them like this:

plugin[fnNameAsync](req, res, Path,function(err){
  if(err)
     res.send(err)
});