I have seen several questions, on Stack Overflow and in other places, asking how to implement an ordered hash, ordered object, or ordered dictionary in Javascript. Here are a few examples:
To me, it appears like according to the official ECMAScript spec, the order of the properties in an object is “implementation dependent”, although most browsers loop over the properties in the order in which they were defined. I can imagine some programmers testing their scripts and seeing everything work fine, unaware that, it may behave in unexpected ways in a few situations, at least in principle.
My question is this: Could they change the spec to specify the order of the properties? To me, it doesn’t seem like it would be too hard, but I don’t know if I am missing something. This would encourage the makers of the few remaining browsers to do what everyone else does and add a useful feature. They would basically be saying that JavaScript interpreters should do what most JavaScript interpreters do anyway. I can’t imagine a change like this causing any sort of compatibility issues.
If this would not be a realistic option, why not? I don’t have any immediate practical goals. I am trying to satisfy my curiosity as to why the language is the way it is.
Specifying the enumeration order of object properties was discussed for ECMAScript 5 but dropped because there was found to be no de facto standard across browsers, from what I can gather.
It’s certainly a reasonable desire, particularly since the rise of JSON.