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JavaScript

Posted by harishn
harishn
3,103 Points

Why do we need separate try/catch block while there is an "error" event that could be delegated using .on() method?

Why do we need separate try/catch block while there is an "error" event that could be delegated using .on() method?

For ex: Referring to tutorial "Handling Parsing and Status Code Errors" under Part 1 of Intro to Node.js, we have code like below:

function printError(error) { console.log(error.message); }

response.on('end', function() { try { } catch (error) { printError(error); } });

response.on("error", printError);

2 Answers

Adam Bowers
Adam Bowers
11,812 Points
Adam Bowers
Adam Bowers
11,812 Points

I may be wrong but on .end is the the completion of the response object. Try/Catch is not Asynchronous, so would suffice for the res.end method to catch any errors.

Whereas on response.on("error", function(error){...}); would be something wrong with the http servers response and would need to be handled asynchronously with a callback function.

Ryan Schurton
Ryan Schurton
13,815 Points
Ryan Schurton
Ryan Schurton
13,815 Points

Hello Harish,

The .on is exclusive to JQuery. If you where working on a project that didn't include JQuery. You would need to use a try/catch to handle your errors.

.on('error') needs to be chained to an element to be tested for errors. So it may be good to check if a certain image loaded. However not effected when you want to check if a certain Variable had a particular value, or if a block of code suddenly failed.

Try/catch offers a variety of properties and methods that can be accessed through the error object. To check the status of your errors.

There is so much information about try/catch I suggest a good old fashion google search.

Good luck.