Merge pull request #3097 from hypothesis/291-detect-existing-h-client

Enable Chrome extension to detect when H is already present on page

h/static/extension/config.js

-function hypothesisConfig() {
-  // Pages on our site can include a meta tag to trigger specific behaviour
-  // when the extension loads.
-  var hypothesisIntent = document.querySelector('[name="hypothesis-intent"]');
-  return {
-    firstRun: hypothesisIntent && hypothesisIntent.content === 'first-run',
-  };
-}

h/static/extension/destroy.js

-if (window.annotator) window.annotator.destroy();
-delete window.annotator;

h/static/scripts/annotator/main.js

@@ -33,8 +33,10 @@ Annotator.Plugin.CrossFrame.Bridge = require('../bridge');
 Annotator.Plugin.CrossFrame.Discovery = require('../discovery');
 
 var docs = 'https://h.readthedocs.org/en/latest/hacking/customized-embedding.html';
+var appLinkEl =
+  document.querySelector('link[type="application/annotator+html"]');
 var options = {
-  app: jQuery('link[type="application/annotator+html"]').attr('href')
+  app: appLinkEl.href,
 };
 
 if (window.hasOwnProperty('hypothesisConfig')) {
@@ -54,5 +56,11 @@ Annotator.noConflict().$.noConflict(true)(function() {
     Klass = options.constructor;
     delete options.constructor;
   }
+
   window.annotator = new Klass(document.body, options);
+  appLinkEl.addEventListener('destroy', function () {
+    appLinkEl.parentElement.removeChild(appLinkEl);
+    window.annotator.destroy();
+    window.annotator = undefined;
+  });
 });

h/static/scripts/test/promise-util.js

+'use strict';
+
 /**
  * Takes a Promise<T> and returns a Promise<Result>
  * where Result = { result: T } | { error: any }.
@@ -9,7 +11,7 @@ function toResult(promise) {
   return promise.then(function (result) {
     return { result: result };
   }).catch(function (err) {
-    return { error: err }
+    return { error: err };
   });
 }