javascript - Using helper methods while templating with Angular JS

Question

Currently in the process of converting a website from its previous templating to Angular. In the previous templating process we were using we were able to call helper methods to display data correctly. For instance:

<script type="text/javascript">
$.views.helpers({
    parseDate: function (jsonDate) {
      if (jsonDate != null) {
        var newDate = Utils.PrettyDate(Utils.ConvertJsonDateToJsDate(jsonDate));
        return newDate;
      }
    }
});
</script>


<div class="post-info">
  <span class="posted-date">Posted {{ :~parseDate(CreatedDate) }}</span>
  &nbsp|&nbsp
  <span>{{ :ReplyCount }} Replies</span>
</div>

This was very nice. Trying to figure out a way to utilize the same type of functionality with Angular as far as templating goes. Is it possible to do something similar? If so how?

Answer 1

If you are only interested in data display, then as pkozlowski.opensource already mentioned, filters are the "Angular way" of formatting data for display. If the existing date filter is not sufficient, I suggest a custom filter. Then your HTML will look more "angular":

<span class="posted-date">Posted {{CreatedDate | dateFormatter}}</span>

The above syntax makes it clear that you're (only) formatting.

Here's a custom filter:

angular.module('OurFormatters', []).
 filter('dateFormatter', function() {               // filter is a factory function
   return function(unformattedDate, emptyStrText) { // first arg is the input, rest are filter params
       // ... add date parsing and formatting code here ...
       if(formattedDate === "" && emptyStrText) {
            formattedDate = emptyStrText;
       }
       return formattedDate;
   }
 });

By encapsulating our filters/formatters into a module, it is also easier to (re)use them in multiple controllers -- each controller that needs them just injects OurFormatters.

Another benefit of filters is that they can be chained. So if someday you decide that in some places in your app empty dates should show nothing (be blank), whereas in other places in your app empty dates should show 'TBD', a filter could solve the latter:

<span class="posted-date">Posted {{CreatedDate | dateFormatter | tbdIfEmpty}}</span>

Or your custom filter can take one or more arguments (the above example supports an argument):

<span class="posted-date">Posted {{CreatedDate | dateFormatter:'TBD'}}</span>