From 43a4671c64dff36f287b2415019520778407a91a Mon Sep 17 00:00:00 2001
From: eight <eight04@gmail.com>
Date: Wed, 28 Nov 2018 12:57:44 +0800
Subject: [PATCH] Change: defer page script injection. Try to inject to head
 (#584)

---
 content/apply.js | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/content/apply.js b/content/apply.js
index 6a83d4e5..bbb6a338 100644
--- a/content/apply.js
+++ b/content/apply.js
@@ -65,10 +65,9 @@ const APPLY = (() => {
     // Since it's easy to spoof the browser version in pre-Quantum FF we're checking
     // for getPreventDefault which got removed in FF59 https://bugzil.la/691151
     const EVENT_NAME = chrome.runtime.id;
-    const usePageScript = CHROME || isOwnPage || Event.prototype.getPreventDefault ?
-      Promise.resolve(false) : injectPageScript();
+    let ready;
     return (el, content) =>
-      usePageScript.then(ok => {
+      checkPageScript().then(ok => {
         if (!ok) {
           const disabled = el.disabled;
           el.textContent = content;
@@ -83,6 +82,14 @@ const APPLY = (() => {
         }
       });
 
+    function checkPageScript() {
+      if (!ready) {
+        ready = CHROME || isOwnPage || Event.prototype.getPreventDefault ?
+          Promise.resolve(false) : injectPageScript();
+      }
+      return ready;
+    }
+
     function injectPageScript() {
       const scriptContent = EVENT_NAME => {
         document.currentScript.remove();
@@ -125,7 +132,7 @@ const APPLY = (() => {
       script.src = src;
       script.onerror = () => resolve(false);
       window.addEventListener(EVENT_NAME, handleInit);
-      document.documentElement.appendChild(script);
+      (document.head || document.documentElement).appendChild(script);
       return promise.then(result => {
         script.remove();
         window.removeEventListener(EVENT_NAME, handleInit);