Check for a value equals to in Ember Handlebar If block helper

The {{#if}} helper can only test for properties, not arbitrary expressions. The best thing to do in cases like this is therefore to write a property computing whatever conditional you want to test for.

personIsJohn: function() {
  return this.get('person') === 'John';
}.property('person')

Then do {{#if personIsJohn}}.

Note: If you find this too limiting, you can also register your own more powerful if helper.