Fix form submission (#129)

* Fix check for radio and checkbox inputs

* Fix GET form submission

* Add example forms for testing

* Refactor query string building

lib/send-request.js

@@ -1,7 +1,11 @@
+var updateQueryString = require("./util/update-query-string");
+
 module.exports = function(location, options, callback) {
   options = options || {}
-  var requestMethod = options.requestMethod || "GET"
-  var requestPayload = options.requestPayloadString || null
+  var queryString
+  var requestMethod = (options.requestMethod || "GET").toUpperCase()
+  var requestParams = options.requestParams || null
+  var requestPayload = null
   var request = new XMLHttpRequest()
 
   request.onreadystatechange = function() {
@@ -24,19 +28,40 @@ module.exports = function(location, options, callback) {
     callback(null, request)
   }
 
-  // Add a timestamp as part of the query string if cache busting is enabled
-  if (this.options.cacheBust) {
-    location += (!/[?&]/.test(location) ? "?" : "&") + new Date().getTime()
+  // Prepare the request payload for forms, if available
+  if (requestParams && requestParams.length) {
+    // Build query string
+    queryString = (requestParams.map(function(param) {return param.name + "=" + param.value})).join("&")
+
+    switch (requestMethod) {
+      case "GET":
+        // Reset query string to avoid an issue with repeat submissions where checkboxes that were
+        // previously checked are incorrectly preserved
+        location = location.split("?")[0]
+
+        // Append new query string
+        location += "?" + queryString
+        break
+
+      case "POST":
+        // Send query string as request payload
+        requestPayload = queryString
+        break
+    }
   }
 
-  request.open(requestMethod.toUpperCase(), location, true)
+  // Add a timestamp as part of the query string if cache busting is enabled
+  if (this.options.cacheBust) {
+    location = updateQueryString(location, "t", Date.now())
+  }
+
+  request.open(requestMethod, location, true)
   request.timeout = options.timeout
   request.setRequestHeader("X-Requested-With", "XMLHttpRequest")
   request.setRequestHeader("X-PJAX", "true")
 
-  // Add the request payload if available
-  if (options.requestPayloadString !== undefined && options.requestPayloadString !== "") {
-    // Send the proper header information along with the request
+  // Send the proper header information for POST forms
+  if (requestPayload && requestMethod === "POST") {
     request.setRequestHeader("Content-type", "application/x-www-form-urlencoded")
   }