context.js

{
  ifequal: function(chunk, context, bodies, params) {
    if (params.left === params.right) {
      return chunk.render(bodies.block, context);
    } else {
      return chunk.render(bodies['else'], context);
    }
  },
  foo: "value",
  bar: "value"
}

output

Hello

template

{#ifequal left=foo right=bar}
  Hello
{:else}
  Goodbye
{/ifequal}