Improve implicit form submission

* Implement the "default button" part of the standard.
* If the submitter is the form, formmethod may be called on it. Check if
  this is the case in the function, and if yes, return the form's method.

2 files changed, 26 insertions, 12 deletions

diff --git a/src/html/dom.nim b/src/html/dom.nim
index 0fac35e7..eec535ad 100644
--- a/src/html/dom.nim
+++ b/src/html/dom.nim
@@ -1819,24 +1819,29 @@ func enctype*(element: Element): FormEncodingType =
 
   return FORM_ENCODING_TYPE_URLENCODED
 
+func parseFormMethod(s: string): FormMethod =
+  return case s.toLowerAscii()
+  of "get": FORM_METHOD_GET
+  of "post": FORM_METHOD_POST
+  of "dialog": FORM_METHOD_DIALOG
+  else: FORM_METHOD_GET
+
 func formmethod*(element: Element): FormMethod =
+  if element.tagType == TAG_FORM:
+    # The standard says nothing about this, but this code path is reached
+    # on implicit form submission and other browsers seem to agree on this
+    # behavior.
+    return parseFormMethod(element.attr("method"))
+
   if element.isSubmitButton():
     if element.attrb("formmethod"):
-      return case element.attr("formmethod").tolower()
-      of "get": FORM_METHOD_GET
-      of "post": FORM_METHOD_POST
-      of "dialog": FORM_METHOD_DIALOG
-      else: FORM_METHOD_GET
+      return parseFormMethod(element.attr("formmethod"))
 
   if element.tagType in SupportedFormAssociatedElements:
     let element = FormAssociatedElement(element)
     if element.form != nil:
       if element.form.attrb("method"):
-        return case element.form.attr("method").tolower()
-        of "get": FORM_METHOD_GET
-        of "post": FORM_METHOD_POST
-        of "dialog": FORM_METHOD_DIALOG
-        else: FORM_METHOD_GET
+        return parseFormMethod(element.form.attr("method"))
 
   return FORM_METHOD_GET
 
diff --git a/src/server/buffer.nim b/src/server/buffer.nim
index 1e97a4bb..24dc7d3d 100644
--- a/src/server/buffer.nim
+++ b/src/server/buffer.nim
@@ -1200,8 +1200,17 @@ type ReadSuccessResult* = object
   repaint*: bool
 
 func implicitSubmit(input: HTMLInputElement): Option[Request] =
-  if input.form != nil and input.form.canSubmitImplicitly():
-    return submitForm(input.form, input.form)
+  let form = input.form
+  if form != nil and form.canSubmitImplicitly():
+    var defaultButton: Element
+    for element in form.elements:
+      if element.isSubmitButton():
+        defaultButton = element
+        break
+    if defaultButton != nil:
+      return submitForm(form, defaultButton)
+    else:
+      return submitForm(form, form)
 
 proc readSuccess*(buffer: Buffer, s: string): ReadSuccessResult {.proxy.} =
   if buffer.document.focus != nil: