title: Validate input type="number" before submitting
body: <p>I'm running into an interesting problem while trying to restrict user input to a number.</p>
  
  <p>My HTML looks like so:</p>
  
  <pre><code>&lt;input name="activeDate" type="number" class="form-control" ng-model="account.tag.activeDate"&gt;&lt;/input&gt;
  </code></pre>
  
  <p>...and my relevant Angular controller code like so(this is inside a click handler):</p>
  
  <pre><code>tag.activeDate = moment.utc().add(tag.activeDate, tag.tagDurationType).toISOString();
  </code></pre>
  
  <p>Unfortunately when I click the button which submits my form and calls that click handler I get this error in my console:</p>
  
  <pre><code>[ngModel:numfmt] Expected `2015-08-27T22:09:18.919Z` to be a number
  </code></pre>
  
  <p>Looks like my input is checked upon submitting, when it's converted to a date within my controller. How do I limit user input to numbers without running into this?</p>