Fix empty strings in default parameters breaking navigation

changelog.md

@@ -1,3 +1,7 @@
+# [5.14.1](https://github.com/TehShrike/abstract-state-router/releases/tag/v5.14.1)
+
+- bug fix: empty strings in default parameters would cause the state router to stop cold without any error message
+
 # [5.14.0](https://github.com/TehShrike/abstract-state-router/releases/tag/v5.14.0)
 
 - functional: replaced the `defaultQuerystringParameters` property on states with `defaultParameters`, which applies to both querystring and route parameters.  If you don't specify `defaultParameters`, `defaultQuerystringParameters` will be checked too (though it will now apply to route parameters as well).  [#91](https://github.com/TehShrike/abstract-state-router/issues/91)

index.js

@@ -226,7 +226,7 @@ module.exports = function StateProvider(makeRenderer, rootElement, stateRouterOp
 			var state = prototypalStateHolder.get(newStateName)
 			var defaultParams = state.defaultParameters || state.defaultQuerystringParameters || {}
 			var needToApplyDefaults = Object.keys(defaultParams).some(function missingParameterValue(param) {
-				return !parameters[param]
+				return typeof parameters[param] === 'undefined'
 			})
 
 			if (needToApplyDefaults) {

test/default-params.js

@@ -199,3 +199,28 @@ test('default parameters on parent states should apply to child state routes', f
 	testWithPropertyName('defaultParameters')
 	testWithPropertyName('defaultQuerystringParameters')
 })
+
+test('empty string is a valid default parameter', function(t) {
+	var state = getTestState(t)
+	var stateRouter = state.stateRouter
+
+	stateRouter.addState({
+		name: 'state',
+		route: '/state',
+		template: {},
+		defaultParameters: {
+			someParam: ''
+		},
+		querystringParameters: [ 'someParam' ],
+		activate: function(context) {
+			t.equal(context.parameters.someParam, '')
+			t.equal(state.location.get(), '/state?someParam=')
+
+			t.end()
+		}
+	})
+
+	stateRouter.go('state')
+}, {
+	timeout: 1000
+})