Thursday, November 26, 2015

Book-Review: Responsive Web Design with AngularJS (Sandeep Kumar Patel)

The book is a low level beginner’s guide to AngularJS and some of its responsive capabilities if you are using AngularJS pure (without twitter - bootstrap). A responsive portfolio-application is built as a show-case to introduce the reader to common problems of the field. Other technologies like SASS and JSON are mentioned and partly shown. The book ends with tool advises like the Chrome-F12-tools and Batarang.
AngularJS topics:
-          Templates and DataBinding (MVW)
-          Partials
-          Router
-          Modules / Controller / Scopes
-          Directives (built-in and custom)
-          Custom Services
-          Events / $Watch
-          Publish-Subscribe with $emit, $broadcast - $on
It was easy to read and with good background information, but I would say that after reading it you are not 100% able to build an AngularJS application responsively (and even not responsively) your own. Further investigations are definitely necessary...

kind regards,

Wednesday, November 11, 2015

Helpful error handling in JavaScript


today I tried to develop an error handling in javascript (more exact: angularjs, but this is as good as meaningless here) that makes sense and is helpful. The following solution is built and tested in Chrome.

First of all: javascript support try/catch blocks we can use by throwing errors

try {
  throw new Error('Whoops!');
} catch (e) {
  alert( + ': ' + e.message);

(see: )
... but this is not the thing I meant...

I wanted to create a central function (error callback, error output method) that can be used to gather further information during development time (e.g. as an error callback for a bad web service rest request; as a usable function to call if an internal object state is unknown => a situation happens that should never happen).

... so I did the following:

            $scope.writeError = function (response) {
                if (true) { // DEBUG
                    console.error('error', response);
                    throw new Error('error');

writeError has an if (line 2) which disables the javascript-console information fast. In angularjs it is easily possible to build this "if" depending on angularjs-constants that can be configured central in a application configuration section.

line 5 sets a coded breakpoint in the javascript console (see: / I adapted the jsfiddle to ); 3 and 4 writes the data (and all its properties) to the console; line 6 throws an exception that can be caught in code and shows similar information to the console.

Attention: the removal of the throw statement can change the application execution logic if try/catch blocks were used outside.

kind regards,

// Update

I should have mentioned 2 things:
- there is window.onerror where you can assign an event handler
- there are frameworks like jsnlog ( ) that sends the error to a server where they can be monitored centrally (angularjs compatible)