Angular 5 - how to make the period field type lowercase in DatePipe

you can just split your date to 2 parts:

{{ today | date : 'EEEE, MMMM d, h:mm' }} {{ today | date : 'a' | lowercase }}
   

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UPDATE

Here is another simple way to achieve it, using built in date pipe and aaaaa matcher (which returns lowercase a or p):

<div>{{ today | date : 'EEEE, MMMM d, h:mm aaaaa\'m\'' }}</div>

Updated Stackblitz: https://stackblitz.com/edit/angular-dcpgzb?file=app%2Fapp.component.html

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ANGULAR JS solution

app.controller('MainCtrl', function($scope, $locale) {
  $locale.DATETIME_FORMATS.AMPMS = ['am', 'pm'];
  $scope.today = new Date();
});

https://plnkr.co/edit/a49kjvOdifXPAvBlmXEi?p=preview