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Debugging

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Debugging Ember

All Ember developers should install the Ember Inspector which provides debugging and development tools for the browser.

You should also become comfortable with the browser debugging tooling for Chrome, Firefox, Safari, and Internet Explorer.

Routing

Log router transitions

app/app.js
export default Ember.Application.extend({
  // Basic logging, e.g. "Transitioned into 'post'"
  LOG_TRANSITIONS: true,

  // Extremely detailed logging, highlighting every internal
  // step made while transitioning into a route, including
  // `beforeModel`, `model`, and `afterModel` hooks, and
  // information about redirects and aborted transitions
  LOG_TRANSITIONS_INTERNAL: true
});

Views / Templates

Log view lookups

config/environment.js
ENV.APP.LOG_VIEW_LOOKUPS = true;

Ember.keys(Ember.TEMPLATES)

Handlebars Debugging Helpers 

{{debugger}}
{{log model}}

Controllers

Log generated controller

config/environment.js
ENV.APP.LOG_ACTIVE_GENERATION = true;

Observers / Binding

See all observers for a object, key 

Ember.observersFor(comments, keyName);

Log object bindings

config/environments.js
ENV.APP.LOG_BINDINGS = true

Miscellaneous

Turn on resolver resolution logging

This option logs all the lookups that are done to the console. Custom objects you've created yourself have a tick, and Ember generated ones don't.

It's useful for understanding which objects Ember is finding when it does a lookup and which it is generating automatically for you.

app/app.js
export default Ember.Application.extend({
  LOG_RESOLVER: true
});

Dealing with deprecations 

Ember.ENV.RAISE_ON_DEPRECATION = true
Ember.ENV.LOG_STACKTRACE_ON_DEPRECATION = true

Implement an Ember.onerror hook to log all errors in production 

Ember.onerror = function(error) {
  Ember.$.ajax('/error-notification', {
    type: 'POST',
    data: {
      stack: error.stack,
      otherInformation: 'exception message'
    }
  });
}

Import the console

If you are using imports with Ember, be sure to import the console:

Ember = {
  imports: {
    Handlebars: Handlebars,
    jQuery: $,
    console: window.console
  }
};

Errors within an RSVP.Promise

There are times when dealing with promises that it seems like any errors are being 'swallowed', and not properly raised. This makes it extremely difficult to track down where a given issue is coming from. Thankfully, RSVP has a solution for this problem built in.

You can provide an onerror function that will be called with the error details if any errors occur within your promise. This function can be anything but a common practice is to call console.assert to dump the error to the console.

app/app.js
Ember.RSVP.on('error', function(error) {
  Ember.Logger.assert(false, error);
});

Errors within Ember.run.later (Backburner.js)

Errors within Ember.run.later (

Backburner has support for stitching the stacktraces together so that you can track down where an erroring Ember.run.later is being initiated from. Unfortunately, this is quite slow and is not appropriate for production or even normal development.

To enable this mode you can set:

Ember.run.backburner.DEBUG = true;
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