js: persist value returned by v8 JSON parser

src/browser/js/Context.zig

@@ -14,6 +14,7 @@ const types = @import("types.zig");
 const Caller = @import("Caller.zig");
 const NamedFunction = Caller.NamedFunction;
 const PersistentObject = v8.Persistent(v8.Object);
+const PersistentValue = v8.Persistent(v8.Value);
 const PersistentModule = v8.Persistent(v8.Module);
 const PersistentPromise = v8.Persistent(v8.Promise);
 const PersistentFunction = v8.Persistent(v8.Function);
@@ -70,6 +71,9 @@ identity_map: std.AutoHashMapUnmanaged(usize, PersistentObject) = .empty,
 // we now simply persist every time persist() is called.
 js_object_list: std.ArrayListUnmanaged(PersistentObject) = .empty,
 
+// js_value_list tracks persisted js values.
+js_value_list: std.ArrayListUnmanaged(PersistentValue) = .empty,
+
 // Various web APIs depend on having a persistent promise resolver. They
 // require for this PromiseResolver to be valid for a lifetime longer than
 // the function that resolves/rejects them.
@@ -149,6 +153,10 @@ pub fn deinit(self: *Context) void {
         p.deinit();
     }
 
+    for (self.js_value_list.items) |*p| {
+        p.deinit();
+    }
+
     for (self.persisted_promise_resolvers.items) |*p| {
         p.deinit();
     }

src/browser/js/js.zig

@@ -148,6 +148,8 @@ pub const Exception = struct {
 };
 
 pub const Value = struct {
+    const PersistentValue = v8.Persistent(v8.Value);
+
     value: v8.Value,
     context: *const Context,
 
@@ -159,7 +161,11 @@ pub const Value = struct {
     pub fn fromJson(ctx: *Context, json: []const u8) !Value {
         const json_string = v8.String.initUtf8(ctx.isolate, json);
         const value = try v8.Json.parse(ctx.v8_context, json_string);
-        return Value{ .context = ctx, .value = value };
+
+        const persisted = PersistentValue.init(ctx.isolate, value);
+        try ctx.js_value_list.append(ctx.arena, persisted);
+
+        return Value{ .context = ctx, .value = persisted.toValue() };
     }
 };