implement choo v5 API (#425)

* implement choo v5 API

* fix tests

* 5.0.0-3

* 4kb now

* bump nanomorph

* 5.0.0-4

* fix missing deps stuff

* 5.0.0-5

* fix travis

* fixup! oops standard

* chooexpose

* fix state passing

* fixup! update example

* fixup! incorporate feedback

* fixup! more docs

* fixup! even more docs

lib/href.js

@@ -0,0 +1,34 @@
+var window = require('global/window')
+var assert = require('assert')
+
+module.exports = href
+
+var noRoutingAttrName = 'data-no-routing'
+
+// handle a click if is anchor tag with an href
+// and url lives on the same domain. Replaces
+// trailing '#' so empty links work as expected.
+// (fn(str), obj?) -> undefined
+function href (cb, root) {
+  assert.equal(typeof cb, 'function', 'sheet-router/href: cb must be a function')
+
+  window.onclick = function (e) {
+    if ((e.button && e.button !== 0) || e.ctrlKey || e.metaKey || e.altKey || e.shiftKey) return
+
+    var node = (function traverse (node) {
+      if (!node || node === root) return
+      if (node.localName !== 'a') return traverse(node.parentNode)
+      if (node.href === undefined) return traverse(node.parentNode)
+      if (window.location.host !== node.host) return traverse(node.parentNode)
+      return node
+    })(e.target)
+
+    if (!node) return
+
+    var isRoutingDisabled = node.hasAttribute(noRoutingAttrName)
+    if (isRoutingDisabled) return
+
+    e.preventDefault()
+    cb(node)
+  }
+}