Derik Whittaker



Knockout JS, Attr Binding and Radio Button Values

When working with Knockout you have the ability to seamlessly bind to a radio buttons via the checked binder.  When working with Radio buttons it is very common to use the value attribute in order to know which radio button was selected.  In fact the code below should be very common if using this binding.


However, when I look at the code above I have 1 issue with it and that is the use of the hard coded value “1” as the value.  I HATE magic strings/values.  Having a raw value like this in your code does not lead to discoverability, I mean what what does ”1” mean?  I would much rather use a constant/enumeration here in order to provide better discoverability.  However, you straight up HTML does not lend itself to this.  For example the code below would NOT yield the results you are expecting.


However, we can harness the power of Knockouts Attr binding to solve our readability problem.  Take a look at the code below


By using the Attr binding I can use the Knockout binding engine to add the value 1 to my HTML at runtime which gives me the correct value as well having my enum value for readability at code time.  Below is the rendered HTML


Till next time,

P.S. If you want to learn more about Knockout watch my Pluralsight Course on Knockout JS

P.S.S. If you want to learn how to transition your XAML skills to HTML you can watch my course on Html for the XAML Developer

Posted 07-11-2013 6:13 AM by Derik Whittaker
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