I know this is too late. But i solved this issue with following Code:
Java Script:
Handlebars.registerHelper('eachData', function(context, options) {
      var fn = options.fn, inverse = options.inverse, ctx;
      var ret = "";
      if(context && context.length > 0) {
        for(var i=0, j=context.length; i<j; i++) {
          ctx = Object.create(context[i]);
          ctx.index = i;
          ret = ret + fn(ctx);
        }
      } else {
        ret = inverse(this);
      }
      return ret;
}); 
HTML:
{{#eachData items}}
 {{index}} // You got here start with 0 index
{{/eachData}}
if you want start your index with 1 you should do following code:
Javascript:
Handlebars.registerHelper('eachData', function(context, options) {
      var fn = options.fn, inverse = options.inverse, ctx;
      var ret = "";
      if(context && context.length > 0) {
        for(var i=0, j=context.length; i<j; i++) {
          ctx = Object.create(context[i]);
          ctx.index = i;
          ret = ret + fn(ctx);
        }
      } else {
        ret = inverse(this);
      }
      return ret;
    }); 
Handlebars.registerHelper("math", function(lvalue, operator, rvalue, options) {
    lvalue = parseFloat(lvalue);
    rvalue = parseFloat(rvalue);
    return {
        "+": lvalue + rvalue
    }[operator];
});
HTML:
{{#eachData items}}
     {{math index "+" 1}} // You got here start with 1 index
 {{/eachData}}
Thanks.