Handlebars currency helper and test

gistfile1.js

Handlebars.registerHelper('currency', function(amount, options) {
  if (typeof(amount) === 'string') { amount = options.contexts[0].get(amount); }
  var rounded = Math.round(amount * 100);
  var dec = rounded % 100;
  var whole = rounded / 100 - dec / 100;
  var decStr = '' + dec;
  return '$' + whole + '.' + decStr + ( decStr.length < 2 ? '0' : '');
});

test("USD", function () {

  //Fails
  var t = Handlebars.compile("{{currency 0.1}}");
  equal(t(), "$0.10", "Passed in cents");

  //Passes
  var t = Handlebars.compile("{{currency amount}}");
  equal(t({amount: 0.15}), "$0.15", "Passed in key");
});

@lazamar JSHint complains about using the Number constructor (since it's type is object instead of number). toLocaleString is available on primitives though: var x = 100; x.toLocaleString(...);

However it is not supported on all browsers, most notably Safari on iOS; it returns the original value.