Is the order of elements in a JSON list preserved?

javascript arrays json list
user437899 picture user437899 · Aug 27, 2011 · Viewed 161.5k times · Source

I've noticed the order of elements in a JSON object not being the original order.

What about the elements of JSON lists? Is their order maintained?

Answer

Jeremy picture Jeremy · Aug 27, 2011

Yes, the order of elements in JSON arrays is preserved. From RFC 7159 -The JavaScript Object Notation (JSON) Data Interchange Format (emphasis mine):

An object is an unordered collection of zero or more name/value pairs, where a name is a string and a value is a string, number, boolean, null, object, or array.

An array is an ordered sequence of zero or more values.

The terms "object" and "array" come from the conventions of JavaScript.

Some implementations do also preserve the order of JSON objects as well, but this is not guaranteed.

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