What is relationship between querySelector and API Level 1?

Question

I checked the MDN website, querySelector is supported by Chrome 1 (2008) as well (?!); I googled few article says querySelector is defined by API Level 1, and the draft of API level 1 is in 2012; how could querySelector come out before 2012?!

Answer 1

Because either:

• It was a proprietary feature that was later standardised or
• It was developed as part of another specification (e.g. within the WHATWG's work) that never made it to a standard and the feature was spun out into a different specification in the meantime

… or both.