From d018ef4f0f76ddba86fb2e5656002669422febde Mon Sep 17 00:00:00 2001
From: carson <carson@leaddyno.com>
Date: Tue, 13 Oct 2020 17:02:15 -0600
Subject: [PATCH] catch on history cache save

fixes https://github.com/bigskysoftware/htmx/issues/209
---
 src/htmx.js                    |  6 +++++-
 test/attributes/hx-push-url.js | 16 ++++++++++++++++
 www/events.md                  |  8 ++++++++
 www/reference.md               |  1 +
 4 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/htmx.js b/src/htmx.js
index 563f057a..87d76f2b 100644
--- a/src/htmx.js
+++ b/src/htmx.js
@@ -1179,7 +1179,11 @@ return (function () {
             while (historyCache.length > htmx.config.historyCacheSize) {
                 historyCache.shift();
             }
-            localStorage.setItem("htmx-history-cache", JSON.stringify(historyCache));
+            try {
+                localStorage.setItem("htmx-history-cache", JSON.stringify(historyCache));
+            } catch (e) {
+                triggerErrorEvent(getDocument().body, "htmx:historyCacheError", {cause:e})
+            }
         }
 
         function getCachedHistory(url) {
diff --git a/test/attributes/hx-push-url.js b/test/attributes/hx-push-url.js
index 3dd6fba0..604a6d3c 100644
--- a/test/attributes/hx-push-url.js
+++ b/test/attributes/hx-push-url.js
@@ -188,4 +188,20 @@ describe("hx-push-url attribute", function() {
         }
     });
 
+    it("saveToHistoryCache should not throw", function () {
+        var bigContent = "Dummy";
+        for (var i = 0; i < 20; i++) {
+            bigContent += bigContent;
+        }
+        console.log(bigContent.length);
+        try {
+            localStorage.removeItem("htmx-history-cache");
+            htmx._("saveToHistoryCache")("/dummy", bigContent, "Foo", 0);
+            should.equal(localStorage.getItem("htmx-history-cache"), null);
+        } finally {
+            // clear history cache afterwards
+            localStorage.removeItem("htmx-history-cache");
+        }
+    });
+
 });
diff --git a/www/events.md b/www/events.md
index 1f5a4c34..f6baf199 100644
--- a/www/events.md
+++ b/www/events.md
@@ -111,6 +111,14 @@ than a single value.
 * `detail.target` - the target of the request
 * `detail.verb` - the HTTP verb in use
 
+### <a name="htmx:historyCacheError"></a> Event - [`htmx:historyCacheError`](#htmx:historyCacheError)
+
+This event is triggered when an attempt to save the cache to `localStorage` fails
+
+##### Details
+
+* `detail.cause` - the `Exception` that was thrown when attempting to save history to `localStorage`
+
 ### <a name="htmx:historyCacheMiss"></a> Event - [`htmx:historyCacheMiss`](#htmx:historyCacheMiss)
 
 This event is triggered when a cache miss occurs when restoring history
diff --git a/www/reference.md b/www/reference.md
index b6186a10..ce4709bf 100644
--- a/www/reference.md
+++ b/www/reference.md
@@ -104,6 +104,7 @@ title: </> htmx - Attributes
 | [`htmx:beforeRequest`](/events#htmx:beforeRequest)  | triggered before an AJAX request is made
 | [`htmx:beforeSwap`](/events#htmx:beforeSwap)  | triggered before a swap is done
 | [`htmx:configRequest`](/events#htmx:configRequest)  | triggered before the request, allows you to customize parameters, headers
+| [`htmx:historyCacheError`](/events#htmx:historyCacheError)  | triggered on an error during cache writing
 | [`htmx:historyCacheMiss`](/events#htmx:historyCacheMiss)  | triggered on a cache miss in the history subsystem
 | [`htmx:historyCacheMissError`](/events#htmx:historyCacheMissError)  | triggered on a unsuccessful remote retrieval 
 | [`htmx:historyCacheMissLoad`](/events#htmx:historyCacheMissLoad)  | triggered on a succesful remote retrieval