Make once and onlyOnce exception safe

More details in issue#1106

2 files changed, 4 insertions, 2 deletions

diff --git a/lib/internal/once.js b/lib/internal/once.js
index 11678dc..f601185 100644
--- a/lib/internal/once.js
+++ b/lib/internal/once.js
@@ -1,7 +1,8 @@
 export default function once(fn) {
     return function () {
         if (fn === null) return;
-        fn.apply(this, arguments);
+        var callFn = fn;
         fn = null;
+        callFn.apply(this, arguments);
     };
 }
diff --git a/lib/internal/onlyOnce.js b/lib/internal/onlyOnce.js
index f4241c8..355ff41 100644
--- a/lib/internal/onlyOnce.js
+++ b/lib/internal/onlyOnce.js
@@ -3,7 +3,8 @@
 export default function onlyOnce(fn) {
     return function() {
         if (fn === null) throw new Error("Callback was already called.");
-        fn.apply(this, arguments);
+        var callFn = fn;
         fn = null;
+        callFn.apply(this, arguments);
     };
 }