1 of 7

Normative: Remove implementation-defined typeof behavior

Daniel Ehrenberg

March 2019 TC39

Igalia, in partnership with Bloomberg

2 of 7

3 of 7

Before

4 of 7

After the change

5 of 7

Does anyone use custom typeof?

  • IE, when used on some debugging interfaces
  • ChakraCore retains some code paths (unclear how to reach)
  • Unclear if there are others

6 of 7

The Web banned implementation-defined typeof

​

​

Great work, Timothy Gu! Thanks for raising this issue.

7 of 7

Let's specify typeof fully for JavaScript!

​

Consensus?