Normative: add Error.prototype.stack (#3878)

ljharb · ljharb · commit bd43c9063fed · 2026-05-22T17:36:04.000+02:00
See tc39/proposal-error-stack-accessor#9
diff --git a/spec.html b/spec.html
@@ -31897,6 +31897,34 @@ <h1>Error.prototype.name</h1>
         <p>The initial value of `Error.prototype.name` is *"Error"*.</p>
       </emu-clause>
 
+      <emu-clause id="sec-get-error.prototype-stack">
+        <h1>Error.prototype.stack</h1>
+        <p>`Error.prototype.stack` is an accessor property with attributes { [[Enumerable]]: *false*, [[Configurable]]: *true* }. The [[Get]] and [[Set]] attributes are defined as follows:</p>
+
+        <emu-clause id="sec-get-error.prototype.stack">
+          <h1>get Error.prototype.stack</h1>
+          <p>The value of the [[Get]] attribute is a built-in function that requires no arguments. It performs the following steps when called:</p>
+          <emu-alg>
+            1. Let _error_ be the *this* value.
+            1. If _error_ is not an Object, throw a *TypeError* exception.
+            1. If _error_ does not have an [[ErrorData]] internal slot, return *undefined*.
+            1. Return an implementation-defined string that represents the stack trace of _error_.
+          </emu-alg>
+        </emu-clause>
+
+        <emu-clause id="sec-set-error.prototype.stack">
+          <h1>set Error.prototype.stack</h1>
+          <p>The value of the [[Set]] attribute is a built-in function that takes an argument _value_. It performs the following steps when called:</p>
+          <emu-alg>
+            1. Let _error_ be the *this* value.
+            1. If _error_ is not an Object, throw a *TypeError* exception.
+            1. If _value_ is not a String, throw a *TypeError* exception.
+            1. Perform ? SetterThatIgnoresPrototypeProperties(_error_, %Error.prototype%, *"stack"*, _value_).
+            1. Return *undefined*.
+          </emu-alg>
+        </emu-clause>
+      </emu-clause>
+
       <emu-clause id="sec-error.prototype.tostring" type="built-in function">
         <h1>Error.prototype.toString ( )</h1>
         <p>This method performs the following steps when called:</p>
@@ -31916,7 +31944,7 @@ <h1>Error.prototype.toString ( )</h1>
 
     <emu-clause id="sec-properties-of-error-instances">
       <h1>Properties of Error Instances</h1>
-      <p>Error instances are ordinary objects that inherit properties from the Error prototype object and have an [[ErrorData]] internal slot whose value is *undefined*. The only specified use of [[ErrorData]] is to identify Error, AggregateError, and _NativeError_ instances as Error objects within `Object.prototype.toString` and `Error.isError`.</p>
+      <p>Error instances are ordinary objects that inherit properties from the Error prototype object and have an [[ErrorData]] internal slot whose value is *undefined*. Specified uses of [[ErrorData]] include to identify <emu-xref href="#sec-error-constructor">Error</emu-xref>, <emu-xref href="#sec-aggregate-error-constructor">AggregateError</emu-xref>, and _NativeError_ instances as Error objects within <emu-xref href="#sec-object.prototype.tostring">Object.prototype.toString</emu-xref> and <emu-xref href="#sec-error.iserror">Error.isError</emu-xref>; as well as for the <emu-xref href="#sec-get-error.prototype-stack">Error.prototype.stack accessor</emu-xref>.</p>
     </emu-clause>
 
     <emu-clause id="sec-native-error-types-used-in-this-standard">
@@ -32032,7 +32060,7 @@ <h1>_NativeError_.prototype.name</h1>
 
       <emu-clause id="sec-properties-of-nativeerror-instances">
         <h1>Properties of _NativeError_ Instances</h1>
-        <p>_NativeError_ instances are ordinary objects that inherit properties from their _NativeError_ prototype object and have an [[ErrorData]] internal slot whose value is *undefined*. The only specified use of [[ErrorData]] is by `Object.prototype.toString` (<emu-xref href="#sec-object.prototype.tostring"></emu-xref>) and `Error.isError` (<emu-xref href="#sec-error.iserror"></emu-xref>) to identify Error, AggregateError, or _NativeError_ instances.</p>
+        <p>_NativeError_ instances are ordinary objects that inherit properties from their _NativeError_ prototype object and have an [[ErrorData]] internal slot whose value is *undefined*. Specified uses of [[ErrorData]] include to identify <emu-xref href="#sec-error-constructor">Error</emu-xref>, <emu-xref href="#sec-aggregate-error-constructor">AggregateError</emu-xref>, and _NativeError_ instances as Error objects within <emu-xref href="#sec-object.prototype.tostring">Object.prototype.toString</emu-xref> and <emu-xref href="#sec-error.iserror">Error.isError</emu-xref>; as well as for the <emu-xref href="#sec-get-error.prototype-stack">Error.prototype.stack accessor</emu-xref>.</p>
       </emu-clause>
     </emu-clause>
 
@@ -32109,7 +32137,7 @@ <h1>AggregateError.prototype.name</h1>
 
       <emu-clause id="sec-properties-of-aggregate-error-instances">
         <h1>Properties of AggregateError Instances</h1>
-        <p>AggregateError instances are ordinary objects that inherit properties from their AggregateError prototype object and have an [[ErrorData]] internal slot whose value is *undefined*. The only specified use of [[ErrorData]] is by `Object.prototype.toString` (<emu-xref href="#sec-object.prototype.tostring"></emu-xref>) and `Error.isError` (<emu-xref href="#sec-error.iserror"></emu-xref>) to identify Error, AggregateError, or _NativeError_ instances.</p>
+        <p>AggregateError instances are ordinary objects that inherit properties from their AggregateError prototype object and have an [[ErrorData]] internal slot whose value is *undefined*. Specified uses of [[ErrorData]] include to identify <emu-xref href="#sec-error-constructor">Error</emu-xref>, <emu-xref href="#sec-aggregate-error-constructor">AggregateError</emu-xref>, and _NativeError_ instances as Error objects within <emu-xref href="#sec-object.prototype.tostring">Object.prototype.toString</emu-xref> and <emu-xref href="#sec-error.iserror">Error.isError</emu-xref>; as well as for the <emu-xref href="#sec-get-error.prototype-stack">Error.prototype.stack accessor</emu-xref>.</p>
       </emu-clause>
     </emu-clause>
 
