-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brendan Eich Sent: Saturday, August 11, 2012 22:57
> As noted, they started out that way 17 years ago. I think WebIDL and > interface-based method definition made onload, e.g., predefined on window > objects, or more recently on Window.prototype. Was this useful? > Was it intended specifically (for window, not just intended generally due to > WebIDL's uniform rules for binding its definitions in JS)? As a developer, the fact that the properties already exist and are set to null is useful for feature-detection. E.g. any of the following will test for the presence of cross-document messaging: "onmessage" in window window.onmessage !== undefined window.onmessage === null // assuming no badly-behaved third-party scripts It is also useful strictly from a development POV, because typing `window.on` in the Firefox or Chrome console gives a list of supported events. FWIW, my mental model is probably closest to these being non-magical own data properties, pre-initialized to null, that the browser will read from and use when it fires the corresponding event. They don't make much sense as accessors to me. _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
