This article is the fourth in a series of working with KnockoutJS and ASP.NET MVC. This article is not strictly about using KnockoutJS with ASP.NET MVC but will show how to create a simple custom binding handler to bind and format date values to HTML elements using Moment JS. As usual, this article will build on the code from the previous articles in the series:
- Getting Started with ASP.NET MVC and KnockoutJS
- Creating a KnockoutJS Model From an ASP.NET MVC Model
- Loading a KnockoutJS model from and ASP.NET MVC controller using ajax
Note a sample project for this series of articles will be available on Github
There isn’t a lot of code to this article; this sample is mostly based on the dynamic model loading sample from a previous article. This sample makes use of the custom binding functionality in KnockoutJS which I’m not going to go through step by step. If you want to understand custom bindings and how they work I suggest reading the documentation on the Knockout website. First up is the custom Knockout binding:
The important parts to notice here are lines 8 and 12 where the code will determine the date format to use (using MomentJS’ formats) and then parse the input string using MomentJS. Next is a simple view which uses the date binding:
On line 18 I then use the new date binding and specify the date format and the custom binding does it’s work to spit out a date in the DD MMM YYYY format. As I mentioned above this isn’t strictly an article about using KnockoutJS and ASP.NET MVC together however I have found it to be very useful. Doing this kind of work on the client-side means that you don’t have to format the date as a string on the serverside and your model can simply return a DateTime object.