Per section 7.1.5 Named Browsing Contexts[1] of the WHATWG HTML specification: > A valid browsing context name or keyword is any string that is either a valid browsing context name or that is an ASCII case-insensitive match for one of: _blank, _self, _parent, or _top. However, the behavior observed is that case-mixed variants of `_top` and `_self` are treated as non-keyword browsing context names. To reproduce, e.g.: 1. `window.open` into `_tOP` or 1. `window.open` into `_seLF` Expected result[2]: For `_tOP`, browser should re-use top-level browsing context, or current if top For `_seLF`, browser should re-use current browsing context Actual result: Browser opens document in new browsing context, treating `_tOP` and `_seLF` as new, named contexts Similar to: https://bugs.webkit.org/show_bug.cgi?id=169748 (_parent) and https://bugs.webkit.org/show_bug.cgi?id=169747 (_blank) Relevant web-platform-tests: https://github.com/w3c/web-platform-tests/pull/5233 [1] https://html.spec.whatwg.org/#browsing-context-names [2] https://html.spec.whatwg.org/#valid-browsing-context-name-or-keyword
*** This bug has been marked as a duplicate of bug 169747 ***