Polymer.Dart in IE

The browser wars are long since over, won by Firefox when it reached 10% market share ca. 2005. Once that inflection point hit, it was impossible to target a single browser without alienating 1 out of every ten potential customers. At this point, it hardly matters which browser is “winning.” If a particular browser or browser version has 10% or more of the market share, we developers have to support it. If a particular browser or browser version has less than 10%, then we have to make a cost-benefit judgment on whether to support it.

That said, I rather like the approach of Dart and Polymer (and others): support only the most recent versions of evergreen (self-updating) browsers. To be sure, applications that are delivered today would ignore a fair portion of potential customers (10%-25% depending on which damn statistics you believe). But the cost of maintaining libraries and codebases for antique browsers is high—often prohibitively so. And as modern, evergreen browsers like Chrome, Firefox and Internet Explorer continue to evolve, the number of ignored potential customers goes down rapidly.

Bottom line: supporting browsers like Internet Explore 10+ is important. I have every reason to expect that Polymer, Dart, and even Polymer.dart will work on IE. But I have not tried it yet. I create a “hello world” type Polymer.dart application (actually, copy it from Patterns in Polymer) and serve it up via pub serve. When run in Dartium, the bound variables update the title and the button randomly changes the color in the same title:



My next step is to add the Polymer transformer to pubspec.yaml so that pub can transform this into JavaScript for other browsers:

name: ie
dependencies:
  polymer: any
  observe: "0.9.0+1"
dev_dependencies:
  unittest: any
transformers:
- polymer:
    entry_points: web/index.html

Only that doesn't work. Even in Dartium, I now find that my Polymer is being ignored. It is almost as if it is not being loaded from the lib directory.

After checking the sample ToDo MVC code, it seems that is exactly what is going on. In there, they have all of the Polymers in sub-directories of web.

So I copy my elements from the lib directory into web/elements:

➜  dart git:(master) ✗ cd web
➜  web git:(master) ✗ mkdir elements
➜  web git:(master) ✗ cd elements
➜  elements git:(master) ✗ cp -r ../../lib/hello* 

Then I update the page to point to the new location of the Polymer:

    <!-- Load component(s) -->
    <link rel="import" href="elements/hello-you.html">
    <!-- Load Polymer -->
    <script type="application/dart">
      export 'package:polymer/init.dart';
    </script>
    <script src="packages/browser/dart.js"></script>

And I restart pub serve. With that, I have my Polymer.dart application serving up properly—even on Internet Explorer:



I will have to dig into the lib vs. web directory locations a bit more. I suspect that I need to package my Polymers for pub deployment rather than serving them from lib. For now, I am happy to have a proof of concept Polymer.dart successfully running under Internet Explorer.


Day #970

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