Yes, but it's not impossible to achieve it in practice. For example, JavaScript JSON.stringify and JSON.parse have well-defined behaviour: > Properties are vi

Yes, but it's not impossible to achieve it in practice. For example, JavaScript JSON.stringify and JSON.parse have well-defined behaviour: > Properties are visited using the same algorithm as Object.keys(), which has a well-defined order and is stable across implementations https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... > The traversal order, as of modern ECMAScript specification, is well-defined and consistent across implementations. Within each component of the prototype chain, all non-negative integer keys (those that can be array indices) will be traversed first in ascending order by value, then other string keys in ascending chronological order of property creation. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... Similarly, Python json module guarantees that "encoders and decoders preserve input and output order by default. Order is only lost if the underlying containers are unordered." Since 3.7 dict maintains insertion order. https://docs.python.org/3/library/json.html https://docs.python.org/3/library/json.html https://docs.python.org/3/library/stdtypes.html#dict https://docs.python.org/3/library/stdtypes.html#dict Yes, JS and Python behaviour are not the same for all cases, however, non-integer keys do maintain order across Python and JavaScript.