fix server render (#443)

lib/document-ready.js

@@ -0,0 +1,16 @@
+var assert = require('assert')
+
+module.exports = documentReady
+
+function documentReady (callback) {
+  assert.notEqual(typeof document, 'undefined', 'document-ready only runs in the browser')
+
+  var state = document.readyState
+  if (state === 'complete' || state === 'interactive') {
+    return setTimeout(callback, 0)
+  }
+
+  document.addEventListener('DOMContentLoaded', function onLoad () {
+    callback()
+  })
+}