doc: specify that errno is a number, not a string

The documentation erroneously described the errno property as an alias for the code property, but that is not the case in the implementation. errno is the error code of the error as a number, and code is the error code of the error as a string. PR-URL: #9007 Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
nodejs · Nov 11, 2016 · 132425a0587e1371bf5a2e5a2e8a8afdd9166d2c · 132425a
1 parent 9a192a9
commit 132425a0587e1371bf5a2e5a2e8a8afdd9166d2c
Showing with 5 additions and 3 deletions.

+5 −3 doc/api/errors.md
diff --git a/doc/api/errors.md b/doc/api/errors.md
@@ -449,13 +449,15 @@ added properties.
 ### Class: System Error

 #### error.code
-#### error.errno

 Returns a string representing the error code, which is always `E` followed by
 a sequence of capital letters, and may be referenced in `man 2 intro`.

-The properties `error.code` and `error.errno` are aliases of one another and
-return the same value.
+#### error.errno
+
+Returns a number corresponding to the **negated** error code, which may be
+referenced in `man 2 intro`. For example, an `ENOENT` error has an `errno` of
+`-2` because the error code for `ENOENT` is `2`.

 #### error.syscall