这些对象键会始终保持相同顺序吗？

Question

I am making multiple objects, then I am JSON.stringify ing them. Then I am turning them into a hash. I need all of the properties to be stringified in the same order so my hashes are consistent. For example:

function createObj(index, value, key) {
    var obj = {
        value: value,
        index: index,
        key: key
    };

    return obj;
 };


console.log(JSON.stringify(createObj(1, 'blue', 'ABC')));   // =>  {"value":"blue","index":1,"key":"ABC"}
console.log(JSON.stringify(createObj(2, 'red', 'DEF')));    // =>  {"value":"red","index":2,"key":"DEF"}
console.log(JSON.stringify(createObj(3, 'green', 'GHI')));  // =>  {"value":"green","index":3,"key":"GHI"}

Can I always expect the keys to be stringified in the order that I have placed them on the object in my createObj function? I do not add any more properties to the objects after they are created.

If I cannot guarantee this order, can you recommend a way to guarantee the order of the keys for this purpose?

EDIT: I realize that when iterating an object the order of the keys is not guaranteed ( for-in and Object.keys ) but would the order be guaranteed for stringify ing it?

Answer 1

The JSON.stringify() documentation at MDN and the ECMAScript Language Specification do not indicate the order in which keys are stringified. While that order my very well be sequential for primitive types like string , number , and boolean , you can't really be sure for objects, functions, arrays, etc. Your best bet would likely be to implement your own version of stringify in order to be 100% certain of the output.