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Polymer Behaviors in ES6

Friday, March 25th, 2016

Being a typical aspect of Object Oriented Design, inheritance, and mixins, provide the means by which modular reuse patterns can be facilitated within a given system. Similarly, Polymer facilitates code reuse patterns by employing the notion of shared behaviors modules. Let’s take a quick look at how to leverage them in Polymer when using ES6 classes.

Implementing Behaviors

Implementing a Behavior is quite simple, just define an object within a block expression or an IIFE, and expose it via a namespace, or module loader of choice:


Then, include the behavior in a corresponding .html document of the same name so as to allow the behavior to be imported by subsequent elements:


Extending Behaviors

After having defined and exposed a given Behavior, the Behavior can then be extended from element classes by defining a behaviors getter / setter as follows:

Once the behavior has been extended, simply import the behavior in the element’s template (or element bundle, etc.) and it is available to the template class:

Try it

Implementing Multiple Behaviors

Similar to individual behaviors, multiple behaviors can also be defined and extended:



In certain cases, I have found it helpful to group related behaviors together within a new behaviors (array) which bundles the individual behaviors together:

Note: As can be seen in the FourthBehavior, a behavior can also be implemented as an Array of previously defined behaviors.

Extending Multiple Behaviors

As with extending individual behaviors, multiple behaviors can also be extended using a behaviors getter / setter. However, when extending multiple behaviors in ES6, there are syntactic differences which one must take note of. Specifically, the behaviors getter must be implemented as follows:

Try it

And that’s basically all there is to it. Hopefully this article helped outline how Polymer Behaviors can easily be leveraged when implementing elements as ES6 classes. Enjoy.

HTML5 Elements: The <base> Tag

Thursday, September 1st, 2011

The HTML5 Specification introduces many new semantic elements, as well as specifications for existing elements; one of which is the <base> Tag, which allows for specifying a root URL from which all linkable elements in a document (hyperlinks, images etc.) are based, as well as a default target for all linkable elements.


  • The <base> Tag provides two attributes; href (Hyper-text Reference) and target, respectively, which have the same semantic meaning as that of a hyperlink.
  • Only a single <base> Tag is to be defined per page and, must be defined before any elements which except a URL are defined (other than the html element).

Note: While the <base> Tag is not new to HTML5, the changes to the a Tag implies a difference (albeit, marginal) as, a Tags are always hyperlinks, or placeholders for hyperlinks.


Like all HTML markup, usage of the <base> Tag is easy and straightforward: Simply add a single <base> Tag in the <head> element of the document and define either a base URL and / or default target attribute.

Defining a default base URL and target:

The above links will all default to a blank target (new page), with each link’s base URL defaulting to “http://somedomain/app”. Individual links can override the base URL as well as the default target.


The <base> Tag is currently supported by all major browsers.

Web Timing Specification

Tuesday, July 20th, 2010

The Web Timing Specification (draft) aims at providing a standard set of APIs which allow for true end-to-end instrumentation of page load times across browsers.

To quote the w3 spec: “This specification (Web Timing Specification) defines an interface for web applications to access timing information related to navigation and elements.” The API is based on the Navigation Timing and Resource Timing interfaces, respectively.

While I haven’t seen this specification mentioned as part of the HTML5 Family before, in many ways I would consider it to be a worthy candidate for membership as it provides a standards based API through which web applications can be tested for load efficiency. This is obviously something quite useful for any web application as, the ability to precisely measure page load times – and implement optimizations as needed – affords developers the opportunity to provide an improved user experience.

Historically, the ability to accurately measure page load times of web applications has been quite challenging for a number reasons. Just knowing when and where to begin is debatable and, determining the best means of doing so can be a challenge in of itself. Regardless of any current strategies being used, the result is never entirely accurate. With Web Timing developers need not be concerned with these specifics as the API provides the ability to truly measure page load times by encompassing the full scope of loading and parsing a page. This includes the time involved to request, receive and render an HTML document.

For more information, try out the examples in the current supported browsers; IE9, Chrome 6.