errors client collection.js

var errors = new Meteor.Collection(null);

Template.my_templ.errors = function () { errors.find().fetch(); };

Template.my_templ.events({
  'submit': function () {
    if ($('#firstName').val() === '') {
      errors.push({ msg: 'First Name Required' });
    }
  }
});

template.html

<template name="my_templ">
  {{#each errors}}
  <div class="alert alert-danger">
    <button type="button" class="close" data-dismiss="alert">&times;</button>
    {{msg}}
    </div>
  {{/each}}
  <input id="firstName" />
</template>