node.js express.js Error handling in View

Question

node.js express.js Error handling in View

I am very new to node.js and express.js and in programming concepts. I already made a basic MVC modeled app on node and express.

My problem is how do you handle error, I got this following code:

exports.submitBloodRequest=function(kaiseki,resView,request){
    var params = {
        bloodCenterId:request.session.centerID,
        bloodTypeId: request.body.bloodType,
        requestQuantity:request.body.numberOfDonors
    }
    kaiseki.createObject('blood_center_request', params, function(err, res, body, success) {
      if(success){
        resView.redirect('/bloodRequest')
      }else{
        //WHAT TO DO HERE?
      }
    });
}

Kaiseki is just a middleware for parse.com, I don't know what to do if it got error. Usually I use ajaxForm.js to look for BadRequest then use javascript to display error message in my view.

I want my error to appear in the same page, where it is success, should I pass a json error to my view?

Or still use ajaxForm.js and instead of res.render or res.redirect I should use res.status(500)

Is there anyway to handle the error and showing it into the view. Without using any javascript to detect BadRequest?

And can a view have a optional variable? In my view If I didnt pass any value on it it gives me error like if i have #{variable} it asks for its value. Can it be made to be optional? Im using Jade Template

node.js
error-handling
express

Answer 1

To respond to an XHR request with an error you can do something like return resView.status(500).send(err); which will send the err object back as JSON. If you want to render an HTML error page instead you can do return resView.status(500).locals({err: err}).render('/errorPage');

You didn't say which template engine you are using but most likely the #{} version will automatically escape HTML characters for you (turn < into <, etc) to avoid XSS attacks and rendering problems whereas !{} will render the contents of the variable directly without escaping, which is dangerous if the variable contains any user-generated content, but necessary if the variable has HTML you want rendered by the browser.