Stage 2 Draft / February 19, 2025

Error Stack Accessor

20 Fundamental Objects

20.5 Error Objects

20.5.3 Properties of the Error Prototype Object

20.5.3.1 Error.prototype.stack

Error.prototype.stack is an accessor property with attributes { [[Enumerable]]: false, [[Configurable]]: true }. The [[Get]] and [[Set]] attributes are defined as follows:

20.5.3.1.1 get Error.prototype.stack

The value of the [[Get]] attribute is a built-in function that requires no arguments. It performs the following steps when called:

  1. Let E be the this value.
  2. If E is not an Object, throw a TypeError exception.
  3. If E does not have an [[ErrorData]] internal slot, return undefined.
  4. Return an implementation-defined string that represents the stack trace of E.

20.5.3.1.2 set Error.prototype.stack

The value of the [[Set]] attribute is a built-in function that takes an argument v. It performs the following steps when called:

  1. Let E be the this value.
  2. If E is not an Object, throw a TypeError exception.
  3. Let numberOfArgs be the number of arguments passed to this function call.
  4. If numberOfArgs is 0, throw a TypeError exception.
  5. If E does not have an [[ErrorData]] internal slot, return undefined.
  6. Perform ? SetterThatIgnoresPrototypeProperties(this value, %Error.prototype%, "stack", v).
  7. Return undefined.

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© 2025 Jordan Harband, Mark Miller

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