Merge pull request #1362 from 0xProject/fix/instant/push-to-history-broken-when-no-onpopstate

[instant] Fix push to history issue on second full render of instant

1 files changed, 5 insertions, 5 deletions

diff --git a/packages/instant/src/index.umd.ts b/packages/instant/src/index.umd.ts
index 449453b56..7391e2844 100644
--- a/packages/instant/src/index.umd.ts
+++ b/packages/instant/src/index.umd.ts
@@ -91,12 +91,12 @@ export const render = (config: ZeroExInstantConfig, selector: string = DEFAULT_Z
     // If the integrator defined a popstate handler, save it to __zeroExInstantIntegratorsPopStateHandler
     // unless we have already done so on a previous render.
     const anyWindow = window as any;
-    if (window.onpopstate && !anyWindow.__zeroExInstantIntegratorsPopStateHandler) {
-        anyWindow.__zeroExInstantIntegratorsPopStateHandler = window.onpopstate.bind(window);
-    }
-    const integratorsOnPopStateHandler = anyWindow.__zeroExInstantIntegratorsPopStateHandler || util.boundNoop;
+    const popStateExistsAndNotSetPreviously = window.onpopstate && !anyWindow.__zeroExInstantIntegratorsPopStateHandler;
+    anyWindow.__zeroExInstantIntegratorsPopStateHandler = popStateExistsAndNotSetPreviously
+        ? anyWindow.onpopstate.bind(window)
+        : util.boundNoop;
     const onPopStateHandler = (e: PopStateEvent) => {
-        integratorsOnPopStateHandler(e);
+        anyWindow.__zeroExInstantIntegratorsPopStateHandler(e);
         const newState = e.state;
         if (newState && newState.zeroExInstantShowing) {
             // We have returned to a history state that expects instant to be rendered.