Preliminary support for Greasemonkey 4.

package.json

@@ -56,7 +56,12 @@
       "GM_listValues",
       "GM_addValueChangeListener",
       "GM_openInTab",
-      "GM_xmlhttpRequest"
+      "GM_xmlhttpRequest",
+      "GM.getValue",
+      "GM.setValue",
+      "GM.deleteValue",
+      "GM.listValues",
+      "GM.xmlHttpRequest"
     ],
     "min": {
       "chrome": "33",

src/meta/jshint.json

@@ -16,11 +16,14 @@
   "globals": {
     "MediaError":   false,
     "Set":          false,
+    "Promise":      false,
+    "BroadcastChannel": false,
     "GM_info":      false,
     "cloneInto":    false,
     "unsafeWindow": false,
-    "chrome":       false<%=
+    "chrome":       false,
-  meta.grants.map(x => `,\n    "${x}": false`).join('')
+    "GM":           false<%=
+  meta.grants.filter(x => !/\./.test(x)).map(x => `,\n    "${x}": false`).join('')
 %><%=
   read('/tmp/declaration.js').match(/^var (.*);/)[1].split(', ').map(x => `,\n    "${x}": true`).join('')
 %><%=

src/platform/$.coffee

@@ -492,6 +492,46 @@ do ->
 # http://wiki.greasespot.net/Main_Page
 # https://tampermonkey.net/documentation.php
 
+if GM?.deleteValue?
+
+  $.syncChannel = new BroadcastChannel(g.NAMESPACE + 'sync')
+
+  $.on $.syncChannel, 'message', (e) ->
+    for key, val of e.data when (cb = $.syncing[key])
+      cb val, key
+
+  $.sync = (key, cb) ->
+    $.syncing[key] = cb
+
+  $.forceSync = ->
+
+  $.delete = (keys, cb) ->
+    unless keys instanceof Array
+      keys = [keys]
+    Promise.all(GM.deleteValue(g.NAMESPACE + key) for key in keys).then ->
+      items = {}
+      items[key] = undefined for key in keys
+      $.syncChannel.postMessage items
+      cb?()
+
+  $.get = $.oneItemSugar (items, cb) ->
+    keys = Object.keys items
+    Promise.all(GM.getValue(g.NAMESPACE + key) for key in keys).then (values) ->
+      for val, i in values when val
+        items[keys[i]] = JSON.parse val
+      cb items
+
+  $.set = $.oneItemSugar (items, cb) ->
+    Promise.all(GM.setValue(g.NAMESPACE + key, JSON.stringify(val)) for key, val of items).then ->
+      $.syncChannel.postMessage items
+      cb?()
+
+  $.clear = (cb) ->
+    GM.listValues.then (keys) ->
+      $.delete keys.map((key) -> key.replace g.NAMESPACE, ''), cb
+
+else
+
   # workaround for Firefox 53 issue
   $.currentValue = {}
   $.GM_getValue = (key) ->
@@ -613,4 +653,5 @@ $.clear = (cb) ->
     try
       $.delete $.listValues().map (key) -> key.replace g.NAMESPACE, ''
     cb?()
+
 <% } %>

src/platform/CrossOrigin.coffee

@@ -63,7 +63,7 @@ CrossOrigin =
       options.overrideMimeType = 'text/plain; charset=x-user-defined'
     else
       options.responseType = 'arraybuffer'
-    GM_xmlhttpRequest options
+    (GM?.xmlHttpRequest or GM_xmlhttpRequest) options
     <% } %>
 
   file: (url, cb) ->
@@ -99,7 +99,7 @@ CrossOrigin =
         return
       callbacks[url] = [cb]
       <% if (type === 'userscript') { %>
-      GM_xmlhttpRequest
+      (GM?.xmlHttpRequest or GM_xmlhttpRequest)
         method: "GET"
         url: url+''
         onload: (xhr) ->