Handlebars checkbox toggle equivalent for Underscorejs

I have the code for Underscorejs to to bind checked attributes for checkboxes, which goes as,

<%= completed ? 'checked' : '' %>

I looked around for the Handle equivalent for this expression and i think ive found it.

if its the case, can anybody help me as to How I can set the Handlebars.registerHelper function under the custom toggle event of the checkbox in Backbone.js ?

Thank you in advance :)