Add DOMException cause

Author: legendecas

index.bs

@@ -14559,12 +14559,19 @@ The {{DOMException}} type is an [=interface type=] defined by the following IDL
 fragment:
 
 <pre class="idl">
+
+dictionary DOMExceptionOptions {
+  any cause;
+  DOMString name;
+};
+
 [Exposed=(Window,Worker),
  Serializable]
 interface DOMException { // but see below note about ECMAScript binding
-  constructor(optional DOMString message = "", optional DOMString name = "Error");
+  constructor(optional DOMString message = "", optional (DOMString or DOMExceptionOptions) nameOrOptions = "Error");
   readonly attribute DOMString name;
   readonly attribute DOMString message;
+  readonly attribute any cause;
   readonly attribute unsigned short code;
 
   const unsigned short INDEX_SIZE_ERR = 1;
@@ -14598,22 +14605,37 @@ interface DOMException { // but see below note about ECMAScript binding
 Note: as discussed in [[#es-DOMException-specialness]], the ECMAScript binding imposes additional
 requirements beyond the normal ones for [=interface types=].
 
-Each {{DOMException}} object has an associated <dfn for="DOMException">name</dfn> and
-<dfn for="DOMException">message</dfn>, both [=strings=].
+Each {{DOMException}} object has associated fields:
+
+*   its <dfn for="DOMException">name</dfn>, which is [=strings=],
+*   its <dfn for="DOMException">message</dfn>, which is [=strings=],
+*   its <dfn for="DOMException">cause</dfn>, which is {{any}} value.
 
 The
-<dfn constructor for="DOMException" lt="DOMException(message, name)"><code>new DOMException(|message|, |name|)</code></dfn>
+<dfn constructor for="DOMException" lt="DOMException(message, nameOrOptions)">
+ <code>new DOMException(|message|, |nameOrOptions|)</code>
+</dfn>
 constructor steps are:
 
-1. Set [=this=]'s [=DOMException/name=] to |name|.
-1. Set [=this=]'s [=DOMException/message=] to |message|.
+1.  Set [=this=]'s [=DOMException/message=] to |message|.
+1.  If |nameOrOptions| is a string, set [=this=]'s [=DOMException/name=] to
+    |nameOrOptions|.
+1.  Else,
+    1.  If |nameOrOptions|'name is present, set [=this=]'s [=DOMException/name=]
+        to |nameOrOptions|'s name, else set [=this=]'s [=DOMException/name=]
+        to "Error".
+    1.  If |nameOrOptions|'cause is present, set [=this=]'s [=DOMException/cause=]
+        to |nameOrOptions|'s cause.
 
 The <dfn attribute for="DOMException"><code>name</code></dfn> getter steps are to return
 [=this=]'s [=DOMException/name=].
 
 The <dfn attribute for="DOMException"><code>message</code></dfn> getter steps are to
 return [=this=]'s [=DOMException/message=].
 
+The <dfn attribute for="DOMException"><code>cause</code></dfn> getter steps are to
+return [=this=]'s [=DOMException/cause=].
+
 The <dfn attribute for="DOMException"><code>code</code></dfn> getter steps are to return the legacy
 code indicated in the [=error names table=] for [=this=]'s [=DOMException/name=], or 0 if no such
 entry exists in the table.