Add readystate change event to XHR

Deal with non-node current target crashing. Builds ontop of abort_signal, but
with the new event-target specific union, I think this will work in for all
future cases.

src/browser/dom/event_target.zig

@@ -23,10 +23,12 @@ const Page = @import("../page.zig").Page;
 const EventHandler = @import("../events/event.zig").EventHandler;
 
 const DOMException = @import("exceptions.zig").DOMException;
-const Nod = @import("node.zig");
+const nod = @import("node.zig");
 
-// EventTarget interfaces
-pub const Union = Nod.Union;
+pub const Union = union(enum) {
+    node: nod.Union,
+    xhr: *@import("../xhr/xhr.zig").XMLHttpRequest,
+};
 
 // EventTarget implementation
 pub const EventTarget = struct {
@@ -39,18 +41,22 @@ pub const EventTarget = struct {
         // The window is a common non-node target, but it's easy to handle as
         // its a singleton.
         if (@intFromPtr(et) == @intFromPtr(&page.window.base)) {
-            return .{ .Window = &page.window };
+            return .{ .node = .{ .Window = &page.window } };
         }
 
         // AbortSignal is another non-node target. It has a distinct usage though
         // so we hijack the event internal type to identity if.
         switch (try parser.eventGetInternalType(e)) {
             .abort_signal => {
-                return .{ .AbortSignal = @fieldParentPtr("proto", @as(*parser.EventTargetTBase, @ptrCast(et))) };
+                return .{ .node = .{ .AbortSignal = @fieldParentPtr("proto", @as(*parser.EventTargetTBase, @ptrCast(et))) } };
+            },
+            .xhr_event => {
+                const XMLHttpRequestEventTarget = @import("../xhr/event_target.zig").XMLHttpRequestEventTarget;
+                const base: *XMLHttpRequestEventTarget = @fieldParentPtr("base", @as(*parser.EventTargetTBase, @ptrCast(et)));
+                return .{ .xhr = @fieldParentPtr("proto", base) };
             },
             else => {
-                // some of these probably need to be special-cased like abort_signal
-                return Nod.Node.toInterface(@as(*parser.Node, @ptrCast(et)));
+                return .{ .node = try nod.Node.toInterface(@as(*parser.Node, @ptrCast(et))) };
             },
         }
     }

src/browser/events/event.zig

@@ -54,7 +54,7 @@ pub const Event = struct {
 
     pub fn toInterface(evt: *parser.Event) !Union {
         return switch (try parser.eventGetInternalType(evt)) {
-            .event, .abort_signal => .{ .Event = evt },
+            .event, .abort_signal, .xhr_event => .{ .Event = evt },
             .custom_event => .{ .CustomEvent = @as(*CustomEvent, @ptrCast(evt)).* },
             .progress_event => .{ .ProgressEvent = @as(*ProgressEvent, @ptrCast(evt)).* },
             .mouse_event => .{ .MouseEvent = @as(*parser.MouseEvent, @ptrCast(evt)) },

src/browser/netsurf.zig

@@ -527,6 +527,7 @@ pub const EventType = enum(u8) {
     mouse_event = 3,
     error_event = 4,
     abort_signal = 5,
+    xhr_event = 6,
 };
 
 pub const MutationEvent = c.dom_mutation_event;

src/browser/xhr/event_target.zig

@@ -39,6 +39,7 @@ pub const XMLHttpRequestEventTarget = struct {
     onload_cbk: ?Function = null,
     ontimeout_cbk: ?Function = null,
     onloadend_cbk: ?Function = null,
+    onreadystatechange_cbk: ?Function = null,
 
     fn register(
         self: *XMLHttpRequestEventTarget,
@@ -86,6 +87,9 @@ pub const XMLHttpRequestEventTarget = struct {
     pub fn get_onloadend(self: *XMLHttpRequestEventTarget) ?Function {
         return self.onloadend_cbk;
     }
+    pub fn get_onreadystatechange(self: *XMLHttpRequestEventTarget) ?Function {
+        return self.onreadystatechange_cbk;
+    }
 
     pub fn set_onloadstart(self: *XMLHttpRequestEventTarget, listener: EventHandler.Listener, page: *Page) !void {
         if (self.onloadstart_cbk) |cbk| try self.unregister("loadstart", cbk.id);
@@ -111,4 +115,8 @@ pub const XMLHttpRequestEventTarget = struct {
         if (self.onloadend_cbk) |cbk| try self.unregister("loadend", cbk.id);
         self.onloadend_cbk = try self.register(page.arena, "loadend", listener);
     }
+    pub fn set_onreadystatechange(self: *XMLHttpRequestEventTarget, listener: EventHandler.Listener, page: *Page) !void {
+        if (self.onreadystatechange_cbk) |cbk| try self.unregister("readystatechange", cbk.id);
+        self.onreadystatechange_cbk = try self.register(page.arena, "readystatechange", listener);
+    }
 };

src/browser/xhr/xhr.zig

@@ -138,6 +138,13 @@ pub const XMLHttpRequest = struct {
         done = 4,
     };
 
+    // class attributes
+    pub const _UNSENT = @intFromEnum(State.unsent);
+    pub const _OPENED = @intFromEnum(State.opened);
+    pub const _HEADERS_RECEIVED = @intFromEnum(State.headers_received);
+    pub const _LOADING = @intFromEnum(State.loading);
+    pub const _DONE = @intFromEnum(State.done);
+
     // https://xhr.spec.whatwg.org/#response-type
     const ResponseType = enum {
         Empty,
@@ -360,6 +367,8 @@ pub const XMLHttpRequest = struct {
         // We can we defer event destroy once the event is dispatched.
         defer parser.eventDestroy(evt);
 
+        try parser.eventSetInternalType(evt, .xhr_event);
+
         try parser.eventInit(evt, typ, .{ .bubbles = true, .cancelable = true });
         _ = try parser.eventTargetDispatchEvent(@as(*parser.EventTarget, @ptrCast(self)), evt);
     }
@@ -923,4 +932,26 @@ test "Browser.XHR.XMLHttpRequest" {
         // So the url has been retrieved.
         .{ "status", "200" },
     }, .{});
+
+    try runner.testCases(&.{
+        .{ "const req6 = new XMLHttpRequest()", null },
+        .{
+            \\ var readyStates = [];
+            \\ var currentTarget = null;
+            \\ req6.onreadystatechange = (e) => {
+            \\  currentTarget = e.currentTarget;
+            \\  readyStates.push(req6.readyState);
+            \\ }
+            ,
+            null,
+        },
+        .{ "req6.open('GET', 'https://127.0.0.1:9581/xhr')", null },
+        .{ "req6.send()", null },
+        .{ "readyStates.length", "4" },
+        .{ "readyStates[0] === XMLHttpRequest.OPENED", "true" },
+        .{ "readyStates[1] === XMLHttpRequest.HEADERS_RECEIVED", "true" },
+        .{ "readyStates[2] === XMLHttpRequest.LOADING", "true" },
+        .{ "readyStates[3] === XMLHttpRequest.DONE", "true" },
+        .{ "currentTarget == req6", "true" },
+    }, .{});
 }